CURRICULUM MATERIALS A BEGINNING ELEMENTARY TEACHER'S PERSPECTIVE AND PRACTICE

CURRICULUM MATERIALS: A BEGINNING ELEMENTARY TEACHER'S

PERSPECTIVE AND PRACTICE

Carrie J. Beyer

Elizabeth A. Davis

School of Education

University of Michigan

contact: cjbeyer@https://www.wendangku.net/doc/d213062141.html,

A paper presented at the April 2007 annual meeting of the National Association for Research in Science Teaching, New Orleans.

This research is funded by a Presidential Early Career Award for Scientists and Engineers (PECASE) grant from the National Science Foundation, REC grant #0092610, as well as a Centers for Learning and Teaching (CLT) grant #0227557. However, any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors. We greatly appreciate the interest and cooperation of the teacher who made this research possible. We also thank the CASES research group at the University of Michigan and members of the Center for Curriculum Materials in Science for their help in thinking about these issues.

CURRICULUM MATERIALS: A BEGINNING ELEMENTARY TEACHER'S

PERSPECTIVE AND PRACTICE

Carrie J. Beyer & Elizabeth A. Davis

University of Michigan

Abstract: Teaching science as explanation is fundamental to reform efforts but is challenging for

teachers, especially new elementary teachers, for whom the complexities of teaching are

compounded by high demands and little classroom experience. Despite these challenges, few

studies have characterized the knowledge, beliefs, and instructional practices teachers need in

order to overcome these difficulties and the role that educative curriculum materials—or

curriculum materials intended to promote teacher learning in addition to student learning—might

play in facilitating their learning about explanations. To address these gaps, this study describes

one beginning elementary teacher’s perspective and practice for giving priority to explanations

when she is provided with educative curriculum materials that aim to support her in fostering

explanations. Analyses showed that the teacher developed new understandings and practices for

fostering students’ explanation construction when using the educative curriculum materials.

However, despite these advancements, she continued to prioritize learning science content above

the importance of building explanations in her goals and practices, in part because she did not see

explanation construction as a strategy for facilitating students’ understanding of science and as an

educational goal in its own right. The paper concludes with recommendations for designing

educative curriculum materials and teacher education programs.

Reforms in science education highlight the need to promote scientific literacy among all students and suggest that students can become part of an informed citizenry by having the opportunity to learn science through inquiry (American Association for the Advancement of Science [AAAS], 1993; National Research Council [NRC], 1996).Developing evidence-based explanations is one fundamental component of inquiry-oriented science. Teaching science as explanation shifts the goal of learning science from acquiring a collection of facts about natural phenomena to developing a deep understanding of the natural world. However, teachers encounter numerous challenges in helping students develop evidence-based explanations (Newton, Driver, & Osborne, 1999). New elementary teachers are especially in need of support due to their limited science subject matter knowledge and lack of teaching experience.

In order to overcome these challenges, many teachers need to develop new knowledge, beliefs, and instructional practices for guiding students’ explanation construction (Haefner & Zembal-Saul, 2004; Newton et al., 1999). Recent research in science education has shown that educative curriculum materials, which include learning supports for both students and teachers, are one potential vehicle for supporting teachers’ learning about science as explanation (McNeill & Krajcik, accepted).

Even though educative curriculum materials may help teachers learn about inquiry, few studies have actually characterized the knowledge, beliefs, and instructional practices that teachers need to possess in order to foster specific inquiry practices. Additionally, few studies have examined how teachers use educative curriculum materials in their practice and what they can learn from them, especially with regard to fostering explanations. This study addresses both of these gaps by examining how one beginning elementary teacher thinks about and engages her

students in developing scientific explanations when she is provided with educative curriculum materials that are intended to support her in learning about this inquiry practice.

Theoretical Framework

Teaching Science as Explanation

To support new insights about how students learn science, standards documents call educators to develop students’ understandings and abilities with regard to scientific inquiry (AAAS, 1993; NRC, 1996). Inquiry environments iteratively engage students in asking scientific questions, designing and conducting investigations to answer those questions, and constructing and communicating explanations. By investigating their everyday world, students use reasoning and thinking skills, in addition to scientific knowledge, to find solutions to real-world problems.

One essential feature of classroom inquiry is the practice of generating evidence-based explanations (Driver et al., 2000; NRC, 2000; Sandvoal, 2003). Drawing from Toulmin’s (1958) argumentation framework, explanation construction has be defined as the practice of stating claims that account for how or why a phenomenon occurs and using evidence and reasoning to support these claims (e.g., Bell & Linn, 2000; McNeill, Lizotte, Krajcik, & Marx, 2006; Sandoval, 2003; Zohar & Nemet, 2002). Thus, teaching science as explanation shifts the focus away from “getting an answer” to “using evidence and strategies for developing or revising an explanation” (NRC, 1996, p.113).

Generating explanations enables students to enhance their understanding of scientific concepts (Bell & Linn, 2000; Coleman, 1998; Zohar & Nemet, 2002). It also helps students develop greater insight into the nature of scientific knowledge and its methods of scientific investigation (Bell & Linn, 2000; Herrenkohl, Palincsar, DeWater, & Kawasaki, 1999; Sandoval, 2003). Engaging students in this practice also enables students to participate in one of the core practices of the scientific community (Driver, Newton, & Osborne, 2000). For these reasons, teaching science as explanation is essential for students’ learning of and about science. Therefore, this study seeks to better understand the ways in which explanation construction can be fostered among students.

The Role of Teachers in Fostering Explanations

Although engaging in scientific explanation is an important learning goal, using data as evidence to support a scientific claim is no easy task (Bell & Linn, 2000; McNeill et al., 2006; Sandoval, 2003). However, limited research findings have shown that even elementary school children can develop explanations when provided with support (Abell, Anderson, & Chezem, 2000; Coleman, 1998; Herrenkohl & Guerra, 1998; Lehrer, Carpenter, Schauble, & Putz, 2000). Research has investigated the role of various tools and artifacts in scaffolding this inquiry practice (e.g., Bell & Linn, 2000; Coleman, 1998; Herrenkohl et al., 1999; McNeill et al., 2006; Reiser, 2004; Sandoval, 2003). Teachers play a pivotal role in structuring and facilitating students’ learning from scaffolding by working synergistically with curricular materials, instructional activities, and learning technologies (Tabak, 2004). Teachers are essential for making new ideas and cultural tools of the scientific community available to students (Driver, Asoko, Leach, Mortimer, & Scott, 1994). They also play a key role in encouraging students to defend and evaluate their assertions in light of data (Abell et al., 2000; Geddis, 1991). Teachers can help students articulate their explanations more fully by discussing the rationale behind scientific explanation, modeling how to reason from data, and making the tacit structure of

explanations explicit (McNeill & Krajcik, accepted). Moderating interactions, probing students’ theoretical positions, translating between students, and assessing students’ explanations are other crucial pedagogical practices teachers use to foster explanations (Crawford, 2000; McNeill & Krajcik, accepted).

Even though teachers can play a key role in helping students construct evidence-based explanations, they typically place little emphasis on the role of evidence in their science teaching. For example, some teachers make authoritative assertions without having students examine evidence in support of these claims (Geddis, 1991). This often occurs because teachers possess limited understandings of how explanations are developed and evaluated (Haefner & Zembal-Saul, 2004) and lack the pedagogical skills needed to help students make sense of data and generate explanations (Geddis, 1991; Newton et al., 1999). In addition, some teachers fail to see constructing scientific explanations as an educational goal in its own right (Sadler, 2006).

In addition to these challenges to teaching science as explanation, new elementary teachers face additional constraints that often prevent them from meeting the high demands of inquiry-based instruction (Davis, Petish, & Smithey, 2006). Due in part to their lack of teaching experience, many new elementary teachers possess little specialized pedagogical content knowledge for science teaching (Abell & Roth, 1992), that is, knowledge of the difficulties that students face in learning specific science concepts and the ways to represent the subject matter to help students understand these ideas (Magnusson, Krajcik, & Borko, 1999). They also have limited and often unstable understandings of their students, their role as science teachers, and their philosophy of teaching (Abell, Bryan, & Anderson, 1998; Bullough & Knowles, 1990). Additionally, new elementary teachers tend to possess weak subject matter knowledge (Cochran & Jones, 1998), often due to the high demands of having to teach topics from multiple science disciplines as well as various subjects other than science. Classroom management issues and pressures to conform to established school norms also decrease teachers’ motivation to teach science (Abell & Roth, 1992; Appleton & Kindt, 2002; Bullough & Knowles, 1990). As a result, some new elementary teachers decide to move away from lessons that incorporate inquiry or choose not to teach science at all during their first years of teaching. New elementary teachers thus need support in order to promote their success as inquiry science teachers.

In order for teachers to overcome challenges to teaching science as explanation, they need to develop new knowledge, beliefs, and instructional practices for giving priority to explanations (Avraamidou & Zembal-Saul, 2005). Specialized knowledge and beliefs for fostering explanations comprise one fundamental aspect of pedagogical content knowledge (PCK) for scientific inquiry (Zembal-Saul & Dana, 2000), which includes knowledge and beliefs of how to “help students understand the authentic activities of a discipline, the ways knowledge is developed in a particular field, and the beliefs that represent a sophisticated understanding of how the field works” (Davis & Krajcik, 2005, p.5). Specialized knowledge, beliefs, and practices for fostering explanations entail an understanding of why engaging students in explanations is important to scientific inquiry and how to help students make sense of data and generate explanations based on evidence (Avraamidou & Zembal-Saul, 2005).

Even though researchers have argued that the development of specialized knowledge, beliefs, and practices for fostering explanations is important, few studies have actually investigated these characteristics (Davis et al., 2006; Keys & Bryan, 2001), especially at the elementary level. To address these gaps, this study aims to examine elementary teachers’ understanding of what it means to teach science as explanation, their ideas about the role of

explanations in their own science teaching, and the difficulties they encounter when putting explanation into practice.

More specifically, this study examines teachers’ specialized knowledge, beliefs, and practices for fostering explanations as they use and enact educative curriculum materials. Educative curriculum materials include embedded features that are intended to support teacher learning, in addition to student learning (Ball & Cohen, 1996; Davis & Krajcik, 2005). Such materials provide opportunities for teachers to learn about and adopt reform-oriented practices as well as to make informed decisions about how to evaluate, adapt, and use the materials. Educative supports can serve as a form of scaffolding for teachers.

The role of scaffolding has often been examined within the context of supporting student learning (Herrenkohl et al., 1999; McNeill et al., 2006); however, this notion can be extended to teachers as well. Educative features embedded in curriculum materials can scaffold teacher learning by providing teachers with expert guidance that enables them to engage in instructional practices that they would not be able to do independently and that fades across the set of curriculum materials to enable teachers to perform these practices on their own (Schneider, Krajcik, & Blumenfeld, 2005). Additionally, curriculum materials, in particular, may play a unique role in scaffolding teacher learning because they are intimately connected to teachers’ daily work and thus can situate their learning in their own practice (Putnam & Borko, 2000), provide ongoing forms of support (Ball & Cohen, 1996; Collopy, 2003), and support reform initiatives on a large scale (Schneider & Krajcik, 2002).

Though conceptualizing educative features as scaffolding may be fruitful, research studies have just begun to investigate the types of educative features that may be beneficial in fostering teacher learning (Schneider & Krajcik, 2002; Schneider, 2006; Smithey & Davis, 2004). Therefore, much still needs to be learned about the kinds of educative features that can effectively support the development of teachers’ knowledge, beliefs, and practice before studies can investigate the effects of fading the supports over time. This study contributes to this work by examining how educative features synergistically support teachers’ learning about teaching science as explanation.

Purpose of the Study & Research Questions

To better understand teachers’ specialized knowledge, beliefs, and practices for giving priority to explanations when provided with educative curriculum materials, this study describes one new elementary teacher’s perspective and practice for fostering explanations and how educative materials support her learning about teaching science as explanation. We use the term ‘perspective’ to describe the teacher’s knowledge and beliefs. Teachers access a blend of both knowledge and beliefs when they talk about their teaching, making it difficult, if not impossible, to distinguish between the two (Magnusson et al., 1999). The research questions guiding this study include the following: When provided with educative curriculum materials that are intended to support teachers in fostering students’ explanations, (1) what is a new elementary teacher’s perspective on the role of scientific explanations in her own science teaching? and (2) what is a new elementary teacher’s practice like for giving priority to explanations?

This study is significant because it deepens our understanding of new elementary teachers’ knowledge, beliefs, and practice for fostering explanations and elucidates their struggles in integrating this inquiry component into their own practice. These improved understandings offer important insights to curriculum developers and teacher educators into the types of experiences they can create to foster new elementary teachers’ development of

knowledge, beliefs, and practices for teaching science as explanation. By providing a concrete example of classroom practice, this study serves as a vehicle for conceptualizing the ways in which teachers give priority to explanations in their science teaching when using educative curriculum materials, which in turn provides a foundation for the design of larger scale studies.

Methods

Research Design

In this study we used qualitative methods to develop a single case study (Yin, 1994). The purpose of developing a case study was to develop rich descriptions of one elementary teacher’s perspective and practice with regard to explanations and to use these descriptions to consider implications for teacher education and the design of educative curriculum materials. This design allowed us to study the teacher’s interactions with educative materials as she was fully immersed within the complexities of the classroom setting and to develop an in-depth understanding of the reasoning underlying her actions. Even though a single case study does not enable us to form generalizations about beginning elementary teachers and the role of explanation in their classroom practice, the descriptions in this study do shed light on an unexplored area of research by illuminating the characteristics of a particular case with regard to one aspect of inquiry-based instruction and the role that educative materials played in supporting this inquiry practice. These descriptions provide other researchers with a deeper understanding of what to look for when they study this specific aspect of teacher knowledge and beliefs in larger scale studies and how to design educative curriculum materials to support teachers in enacting inquiry-based instruction. Research Participant

We selected Catie (a pseudonym), a third-year second grade teacher, to participate in this study. Catie was a female, white teacher in her mid-twenties and thus was typical of new elementary teachers with regard to gender, race, and age. However, Catie was atypical from her peers because of her strong emphasis on having her students learn science content and her strong reflective disposition (Abell et al., 1998). Moreover, Catie viewed herself as a science teacher, not as a generalist, as most elementary teachers view themselves (Meadows & Koballa, 1993). She participated in many professional development opportunities to develop her science teaching. She joined the National Science Teachers Association, a science teaching professional organization, and began a masters degree program in science education.

Catie was a participant in a longitudinal study exploring new elementary teachers’ learning about science teaching. In this larger study, she taught several units from the CASES website, an online learning environment that provides new elementary teachers with educative curriculum materials intended to help teachers develop an understanding of inquiry-oriented science teaching (https://www.wendangku.net/doc/d213062141.html,; see Davis, Smithey, & Petish, 2004). In this study, Catie enacted the CASES plant unit; this was her first time teaching this unit. She received no additional professional development along with the materials.

Instructional Context & Curriculum Materials

This study took place in a second-grade classroom at a parochial school in southeast Michigan. The class consisted of 30 second-grade students, mostly from the same socio-economic and ethnic background (i.e., white, middle class families). At the start of the study, Catie was teaching a unit on animals that she had designed. She drew from a variety of resources in developing this unit. She enacted the animal unit before teaching the CASES plant unit, which was her final science unit of the school year.

The educative curriculum materials for the plant unit included teacher materials and student worksheets. The unit was designed to engage K-2 grade students in a 6-week extended inquiry on plants, with each week of instruction containing two to four days of instruction. This unit consisted of seven lessons that engaged students in making observations and using their observations as evidence to form written explanations. The materials defined an explanation as a scientific claim supported by evidence drawn from prior experiences, observations, experimental data, and/or reading material. For example, in explaining how a cocklebur is dispersed, students were asked to state a claim, such as, “A cocklebur is dispersed by animals,” and to back up their claim with evidence, such as, “I think this seed moves in this way because it has hooks, and seeds with hooks stuck to my sock during the sock walk.” The materials provided students with detailed questions and sentence starters to facilitate their explanation construction. Lesson topics within the materials included the location of seeds, grouping of seeds, seed dispersal, seed parts, plant usage, plant growth requirements, and an open investigation exploring student-generated questions. Table 1 includes a list of lessons from the plant unit, the date they were taught, and a description of the inquiry tasks that were included in each lesson plan description.

Table 1

Summary of Lessons as Written in Plant Unit

Lesson and Date Description of Inquiry Tasks

and build evidence-based explanations.

2Grouping Seeds, 5/5/05Make and record observations, group seeds based on different criteria, and build evidence-based explanations.

3Seed Dispersal, 5/10/05, 5/12/05 Make and record observations of a cocklebur and form predictions. Make and record observations of seeds collected on a walk and form predictions. Design their own seed and build evidence-based explanations about how it moves.

4Seed Parts, 5/16/05Form predictions, make and record observations of seed parts, and

build evidence-based explanations.

5Sunlight Investigation, 5/17/05, 5/19/05,

5/23/05, 5/26/05Set-up experiment to see if plants need sunlight, form predictions, make and record observations over several days, and build evidence-based explanations.

6Plant Investigation, 5/17/05, 5/19/05,

5/23/05Extended plant investigation driven by student questions. Set-up experiments, form predictions, make and record observations, and build evidence-based explanations.

7Plant Usage, 5/31/05Take field trip to farm or grocery store. Build evidence-based

explanations.

The plant unit was designed to support teacher learning, in addition to student learning, specifically with regard to explanations. Guided by the design heuristics developed by Davis and Krajcik (2005), four types of educative features were developed. First, the materials contained narrative “images of inquiry,” which are fictional vignettes about how a teacher addresses a specific challenge in his or her practice by reflecting on and adapting curriculum materials to address the particular need (Smithey & Davis, 2004; Davis & Krajcik, 2005). In the plant unit, the narratives described how a teacher named Peg engaged her students in different inquiry practices, with an emphasis in some stories on how she helped her students use evidence to develop scientific explanations. Second, responses to “Why?” and, “How?” questions were developed in order to provide teachers with general rationales for why certain aspects of explanation construction are important and general suggestions for how they might integrate such aspects into their own practice (Davis et al., 2004). Third, lesson-specific supports were embedded within the lesson plan description; these supports provided rationales for lesson-specific instructional approaches that aimed to foster students’ explanations and examples of scientific explanations that students might give to particular lesson questions. These lesson-specific supports also provided examples of students’ alternative ideas about explanations and suggestions for how to deal with those ideas. Finally, examples of student answers to assessment questions and descriptions of how the answers counted as scientific explanations were embedded within each lesson assessment. These examples were intended to guide teachers’ thinking about the kinds of scientific explanations students might make in each particular lesson. Table 2 includes examples of these four types of features that aimed to help teachers give priority to explanations in their science teaching

Table 2

Types and Examples of Educative Supports for Giving Priority to Explanations Support Type Examples of Supports from Plant Unit

“Images of Inquiry”back to the classroom and eagerly began removing seeds from their socks. However, when they began drawing their ideas about how their seeds moved, the students found this difficult. They could come up with ideas about how seeds travel, but Peg noticed that their ideas weren't connected to specific seed features. So Peg decided to introduce her students to the term “evidence.” Each student chose 1 seed and gave their opinion (or claim) about how it traveled. Then, the class asked the person what their evidence was. The student then had to point to a feature on the seed that supported his or her claim. This established an important ritual in their classroom -- supporting explanations with evidence -- that will be important throughout this unit. It also helped guide students through this difficult task.

Support?Engages students in working and thinking like scientists (For example, in science, opinions are judged by how strongly they are supported by

evidence. Students often think any opinion is as valid as any other.)

?Facilitates problem solving skills & inquiry abilities.

?Facilitates understanding of content.

How can I help students draw conclusions based on evidence?

Encourage students to draw conclusions based on evidence by…

?working with peers to analyze the data collected during an investigation

?using the data as evidence when drawing conclusions

?asking questions like, What data should we keep? What patterns exist in the data? What explanations account for the patterns?

Lesson-Specific Support Asking WHAT and WHY questions helps students form explanations. WHAT questions prompt students to state their opinion or to make a CLAIM. For example, students might say, "Seeds come from apples." This explanation is not complete, however. Students also need to give some sort of EVIDENCE to support their claim. WHY questions prompt students to use prior experiences, observations, experimental data, or reading material as EVIDENCE for their claim. For example, students might say, "I think seeds come from apples BECAUSE I once ate an apple and saw little black seeds inside it." In these ways, find opportunities to ask your students WHAT they think and WHY they think what they do in order to help them make complete explanations.

Supports for Assessment in Student Worksheets The questions that will be asked on the assessment include the following: ?Where do seeds come from? (Possible Answer: Students might make the CLAIM that seeds come from fruits and vegetables.)

?During your seed activity, what did you do or see that makes you think this? (Possible Answer: Students might suggest that they know seeds come from fruits and vegetables BECAUSE they found seeds inside both apples and pumpkins during the activity. Thus, this question prompts students to use their observations as EVIDENCE to support a claim.)

We did not attempt to disentangle the effects of specific supports in the educative curriculum materials on Catie’s perspective and practice. Instead, we examined how the various features within the educative materials synergistically supported, or failed to support, Catie in fostering students’ explanations. This design limited the types of assertions we could make about the effectiveness of individual educative features. However, this study provides insight into the role the materials played overall in Catie’s enactment of the plant unit.

Data Collection

The primary data sources for this study included field notes of classroom observations collected during the animal and plant units and three audio-taped, semi-structured interviews with Catie (approximately 50-70 minutes each). Secondary data sources included student artifacts as well as various other documents capturing aspects of Catie’s practice. Table 3 summarizes the connections between the data sources and the research questions as well as the hypothesized outcomes for each research question.

Table 3

Analysis Structure for All Data Sources

Data Sources

Hypothesized Analysis Questions

O b s e r v a t i o n s I n t e r v i e w s S t u d e n t W o r k L e s s o n P l a n s

D a i l y L o g s

R e f l e c t i o n Outcomes

RQ1. What is a new elementary teacher’s perspective on the role of scientific explanations in her own science teaching, when she is provided with educative curriculum materials that are intended to support her in learning about this inquiry practice?

1a. How does Catie define explanation? X X Teacher espouses definition recommended in materials. importance of having her students construct explanations? X X construction as important and gives several reasons why. 1c. What are Catie’s learning goals for her students? X X X Teacher wants students to

develop evidence-based

explanations for each lesson.

RQ2. What is a new elementary teacher’s practice like for giving priority to explanations, when she is provided with educative curriculum materials that are intended to support her in fostering those explanations?

Catie frequently employ in her science teaching, and how do they relate to fostering students’

explanations?

X X X practices support students’

explanation construction.

2b. What specialized practices (if any) does Catie use for giving priority to explanations? X X X X X Teacher engages in several practices to support students’ explanation construction. 2c. How do Catie’s assessment practices and views shape the kinds of explanations students make? X X X Teacher wants students to

develop evidence-based

explanations on assessments.

We observed four lessons from the animal unit and used these observations to better understand what instructional practices Catie used with her students in teaching science and the role that explanations played in her science instruction before enacting the plant unit. Additionally, we observed five lessons from the plant unit. These observations enabled us to characterize Catie’s use of the educative materials, any adaptations she made to the lessons, and the specialized practices she used to give priority to explanations during instruction.

In addition to classroom observations, we also interviewed Catie three times, once during the animal unit and once during and after the enactment of the plant unit. Interview questions centered on Catie’s learning goals and instructional practices during the animal and plant units,

assessment views and practices, and feedback on lesson activities and worksheets from the plant unit. During these interviews, we avoided using the terminology presented in the educative curriculum materials (e.g., claim, evidence, explanation) to allow Catie to freely express her ideas without feeling like she had to adopt the ideas/language presented in the plant unit. However, when she did use these terms, we asked Catie to elaborate on her ideas in order to make the meaning behind these words transparent during our conversations. Appendix A includes the protocols used in these interviews.

We also gathered a variety of other artifacts and documents to complement the data collected from the field notes and teacher interviews. We collected student work from the plant unit, including the students’ pre-/post-tests and lesson worksheets. We also collected two daily logs capturing Catie’s self-report of features in her instructional practice. (Catie had completed daily logs before as part of the larger study of which this one is a part and thus was familiar with their structure and content.) We also collected worksheets and assessment tasks from the animal unit and a teacher lesson reflection in response to feedback questions given midway through the plant unit enactment. Appendix B includes the questions used in the teacher lesson reflection. Finally, Catie had highlighted sections of lesson plans from the plant unit and jotted notes in the margins to help her better use the materials. Therefore, at the conclusion of the study, we also asked for and collected copies of her marked-up lesson plans.

Data Analysis

In analyzing the data, we developed several analysis questions to elaborate upon our two main research questions. These questions emerged from key themes in the data and are outlined in Table 3. We used these questions to guide the development of a coding scheme that reflected the predominant themes in the data. The research literature also informed the development of a coding scheme by drawing our attention to possible themes in the data. The coding scheme was developed through an iterative process of uncovering emergent themes related to each analysis question, coding the data with regard to these themes, modifying the themes as appropriate, and recoding the data with a revised coding scheme (Miles & Huberman, 1994). After multiple iterations of analysis and revision of themes, we developed a finalized coding scheme and recoded all the data using it.

After identifying themes and patterns in the data, we generated preliminary assertions for each analysis question based on the data and tested their viability by seeking both confirming and disconfirming evidence from multiple data sources (Erickson, 1986). We then triangulated data sources to support the most robust assertions (Johnson, 1997; Krefting, 1991). We were also able to triangulate against data from the larger longitudinal study of which this was a part (e.g., Forbes & Davis, in review). A single case study was then constructed to describe Catie’s perspective and practice with regard to fostering students’ explanations. To enhance the validity of the study, a second independent rater coded a subset of the data (15%) using the same coding scheme. We achieved over 90% interrater reliability and subsequently resolved all disagreements through discussion and clarified the coding key accordingly. We also discussed emerging findings at regular meetings with impartial colleagues; this peer review process provided further feedback on our emergent themes and contributed to the credibility of the assertions in the case study (Lincoln & Guba, 1985).

Results

This section characterizes Catie’s perspective and practice with regard to helping her students construct explanations, while enacting educative curriculum materials that were intended to support her in fostering those explanations. In characterizing Catie’s perspective on explanations, we first describe how Catie defined the concept of explanation and then describe how she viewed its level of importance in her practice. Next we describe her learning goals for her students during the plant unit. In characterizing her teaching practices, we describe some of Catie’s generalized instructional practices and how they relate to fostering students’ explanations as well as some of her specialized practices for giving priority to explanations. We conclude by detailing the ways in which Catie assessed her students’ explanations and describing her perspective on why some of her students developed inaccurate explanations.

Catie’s Perspective on the Role of Explanations in her Science Teaching How does Catie define explanation? Even though the educative curriculum materials defined an explanation as a claim supported by evidence, it was uncertain whether Catie would define explanations in the same way. Therefore, the data was analyzed to determine how she defined this concept, whereby two themes emerged. Catie broadly defined explanation as a response that provides clarifying details and as a response that includes a general reason why students think their answer is right. However, after teaching the plant unit, Catie articulated a more sophisticated perspective, defining explanation as a response that contains students’ observations as evidence in support of a claim. These themes are described below.

In the first and third interviews, Catie completed a daily log on the most recent lesson she had taught. In the daily log, she selected several items that she thought best characterized what her students had done in class. For both of the lessons, Catie said her students had “made sense of data or evidence,” “used evidence in responding to questions,” “developed explanations based on evidence,” “connected explanations to scientific knowledge,” and “communicated explanations.” In clarifying why she had selected particular items, Catie explained what she had meant by having her students “develop explanations based on evidence,” saying, If they give me an answer, for example, then I say, ‘Well, tell me more,’ or, ‘I don't understand exactly. Elaborate. Expand on that.’ That would be developing their explanation, like making it more understandable to the person they're telling. ‘Give me some more words to describe what you’re thinking about.’ (Interview 1, 4/28/05)

Catie saw an explanation as a detailed response that allows students to expand on their thinking. However, she did not specify what these details would entail.

During the study, Catie also defined explanation as a response that includes a general reason why students think their answer is right. For example, in explaining her responses to the daily logs, Catie emphasized this idea that an explanation provides some sort of reasoning for why students think their idea is right. She said,

I don’t necessarily look for the right answer as much as I look for, ‘If you’ve given me a

yes or no, answered the question, have you given me a reason why you think it’s that way?’ (Interview 3, 6/7/05)

Here, Catie clarified that an explanation needs to include some sort of reasoning. However, she did not specify what this reasoning would entail. Catie explained that in an explanation she wants her students to describe why they think something happened a certain way, thereby providing a general reason why they think their claim or answer is right.

At the end of the plant unit enactment, a different perspective with regard to explanation emerged. In the third interview, Catie began to talk about an explanation as not just any detailed response but, more specifically, as a response that includes students’ observations and actions in support of a particular answer or claim. She said,

[An explanation is] giving a more detailed answer so if somebody else wasn’t there doing the experiment with you or was reading it out at home, that they would understand what it was that you did, what it was that you saw, and could understand why you came to the conclusion that you did without being in the setting that you were in. (Interview 3, 6/7/05)

Catie began to articulate a more refined definition of an explanation by unpacking her ideas about what it means to have students give a “detailed answer.” She clarified that these details include students’ observations and actions and that they are used as evidence to explain why students arrive at the conclusion that they did.

Additionally, at the end of the plant unit enactment, Catie became more explicit about her ideas about what it means to have students give “reasoning” in their explanations. For example, in evaluating some of her students’ explanations from the Seed Dispersal lesson, Catie explained that she wanted her students to provide descriptions of what they had seen on their seed so that she could see their reasoning for the answer they gave:

‘What have you done or seen?’ like, I see that they give some reasons why … you know the last one, ‘It got there by animal fur.’ ‘It’s pointy so it will stick on the animal.’ That kind of an answer is a good reason. That tells me that they’ve looked at the picture, that there’s some aspect or characteristic of that seed that’s given them a thought in their head that this is the right reason. (Interview 3, 6/7/05)

Here, Catie specified that having students “give a reason” in an explanation meant having them use their observations as evidence for a claim. These excerpts show that Catie’s understanding of explanation became more refined by the end of the plant unit enactment as she became more explicit about what it means to give a “detailed answer” or “reasoning” in an explanation. In these ways, Catie’s perspective on explanation became more closely aligned with the educative curriculum materials.

How does Catie view the importance of having students construct explanations? Even though the educative materials emphasized building explanation as an important inquiry practice, it was uncertain whether Catie would also view it as important in her teaching of the plant unit. The analysis of the interview data and the jottings in her lesson plans showed that Catie did view this inquiry practice as important for two reasons. She explained that having students build explanations helps her elucidate students’ understanding of the content and helps students practice clearly communicating their ideas to others. However, even though Catie recognized these benefits, she never saw this practice as helping her students learn the science content. These themes are discussed below.

In her lesson plans from the plant unit, Catie discriminately marked up certain sections in the materials, including the materials lists, teacher preparation, lesson plan directions, and science background information. In addition to these markings, Catie highlighted ideas pertaining to fostering explanations in all of the lessons except one. In several lessons Catie highlighted the questions she planned to ask her students, often underscoring both the content-based questions as well as the questions that prompted students to give evidence for their answer. For example, Catie highlighted the sentences, “Write how they think [the seed] travels” and “WHY they think it travels in this way.” Additionally, Catie highlighted several lesson-specific

supports that were intended to help her foster evidence-based explanations. Catie could have easily skipped over these supports because they were set off by italics; however, Catie not only read these sections but also highlighted phrases within them that she thought were important. For instance, Catie highlighted the sentences, “Asking WHAT and WHY questions helps students form explanations…[Find opportunities to ask your students] WHAT they think and WHY they think.” By taking the time to highlight sections related to fostering students’ explanations, Catie emphasized the idea that she viewed this inquiry practice as important.

In the interviews, Catie expressed this same idea and highlighted several reasons. First, Catie explained that having students engage in this inquiry practice is important because it benefits her as a teacher by helping her determine if her students understand the science content. For example, she said, “It’s important always to get the reason why because when you think, oh yeah, they’ve got it. ‘Uh uh, you thought wrong’” (Interview 3, 6/7/05). Having her students explain their reasoning in their explanations enabled Catie to know if her students had understood the science content or not. Catie also explained that she always looks for her students’ reasoning because a simple yes or no response is inadequate for her to gauge whether her students understand the concepts in the lesson.

Second, Catie explained that having students build explanations benefits her students. For example, she described explanation construction as a way for her second graders to clarify what they are thinking so that others can know how they arrived at the conclusion that they did: Sometimes the kids will say things to me and I have no idea what you're saying at all. ‘I don't understand. Can you give me some other words to describe what you're thinking about?’ I mean that's not even only in science but in other things as well. ‘Give it to me in

a sentence. I don't know what you're saying or, give me some more words to help

because I'm not sure what you're talking about.’ (Interview 1, 4/28/05)

By encouraging students to expand on their thinking and use details to develop an explanation, Catie explained that students are able to elaborate on their thinking and practice clearly communicating their thoughts to others. Additionally, Catie not only viewed this inquiry practice as important in science but even stressed its importance in other subjects as well.

Catie conveyed in many ways the idea that constructing explanations was important to her in teaching the plant unit. In the lesson plans, Catie highlighted ideas related to fostering explanations, and in the interviews, explained how this inquiry practice benefited both her and her students. However, despite these benefits, Catie never mentioned the idea that she could use this inquiry practice to help her students develop an understanding of the science content.

What are Catie’s learning goals for her students?It was uncertain whether Catie would uphold the same learning goals that were espoused by the educative materials, that is, to develop both students’ understanding of the science content and ability to construct explanations. Therefore, the interview transcripts and lesson reflection were analyzed to uncover Catie’s learning goals for both the animal and plant units. The data analysis revealed that during the animal unit, Catie’s learning goals emphasized only science content, but during the plant unit, they began to emphasize a dual focus on content and explanations for some lessons. However, for others lessons in the plant unit and in the unit assessment, Catie emphasized only science content in her learning goals, because she viewed constructing explanations as appropriate only when students were engaged in experimental work. These themes are explored below.

Throughout the animal unit, which Catie taught directly before the plant unit, Catie’s learning goals placed a great deal of importance on scientific knowledge with no emphasis on having her students build explanations. For example, she said, “The main goals for the kids were

to understand the differences between animals with bones and animals without bones; to understand the main groups of the animals like mammals, birds, whatever. And their habitats and adaptations” (Interview 1, 4/28/05). Here, Catie’s learning goals for the animal unit lessons detailed what she wanted her students to know without any emphasis on having her students explain how they had come to know it.

Additionally, for the animal unit assessment, Catie placed a great deal of importance on learning science content with no emphasis on having her students build explanations. The study guide that she designed consisted of a list of vocabulary words with definitions and examples, and the test she gave included only matching, identification, and true/false questions. Catie explained that “there was a lot of memorization [on the animal unit test] so [the students] would know the vocab because that’s one of the main things in science” (Interview 3, 6/7/05). Therefore, before teaching the plant unit, Catie’s learning goals stressed the importance of learning science concepts with no emphasis on learning to build scientific explanations.

However, in three lessons from the plant unit, Catie’s learning goals began to emphasize the importance in having her students not only develop an understanding of the content but also use their observations to build scientific explanations. For example, in the Seed Dispersal lesson, Catie wanted her students to understand how seeds are dispersed and to have them use their observations of seed features to explain how specific seeds moved. She said, “I wanted them to be able to look at a seed and analyze its characteristics, which help to make it move. I wanted them to understand the way of movement was and how we could tell that from the seed’s characteristics” (Lesson Reflection, 5/19/05). Similarly, in the Sunlight Investigation lesson, Catie wanted her students not only to know that plants need sunlight but also to use their observations to explain how they know this. She said, “I wanted them to use what they saw happen to their plant as evidence for giving the answer of yes or giving the answer no [about whether plants need sunlight or not]” (Interview 3, 6/7/05). Therefore, for several lessons in the plant unit, Catie’s learning goals were consistent with the educative curriculum materials because she aimed to provide opportunities for her second graders to build evidence-based explanations, in addition to learning the science content.

However, like the animal unit, Catie’s learning goals for some of the plant unit lessons emphasized only the science content, even though these lessons were intended to emphasize both learning concepts and developing explanations. For example, for the Seed Parts lesson, Catie emphasized only content learning goals for her students, saying, “I was hoping that the students would understand that there are three main parts and what their names are (embryo, food supply and seed coat). I wanted them to understand the function of each and why it was necessary to have these parts” (Lesson Reflection, 5/19/05). In this lesson, Catie wanted her students to only learn the names of the seed parts and their functions, not engage in the scientific practice of building explanations. Consequently, Catie deemphasized the importance of having her students make observations of the different seed parts and use their observations to understand each part’s function, which were learning goals espoused by the educative curriculum materials.

Additionally, for the plant unit assessment, Catie explained that she wanted her test only to assess what science content her students had learned, not how they had come to know it. For example, she described the kinds of questions she wanted to include on the unit test, saying,

I think I would probably have a diagram so they would be able to label simple parts like

the petals of the plant or the roots of the plant or the root hairs and I’d give them a word box and all that, and like asking them what are the things that makes the plant living that

would be important for them to have and, to give them a couple of pictures of seeds and ask them how they travel. (Interview 3, 6/7/05)

Here, Catie’s ideas for a unit test included assessing her students’ knowledge of plant parts, living things, and modes of seed dispersal but not students’ ability to build explanations.

Additionally, in commenting on whether she would use our post-test as her unit test, Catie indicated that she liked the content-based questions but not the questions that asked students to explain their ideas. She explained her reasoning for this response, saying, “I think that those kind of questions, like, ‘What have you done or seen [that makes you think this]?’ is more important when you’re doing an experiment but not necessarily on a test” (Interview 3, 6/7/05). This excerpt uncovers why for the unit assessment Catie believed it was only important for her second graders to demonstrate an understanding of the science content.

In sum, during the animal unit, Catie’s learning goals only emphasized science content, but during the plant unit, they began to incorporate a dual emphasis on learning content and building explanations, showing consistency with the goals in the educative materials. However, for some of the lessons and the unit assessment in the plant unit, Catie only emphasized the importance of having her students understand the science content. She explained that having students build explanations was only relevant when students were engaged in experimental work.

Summary.Initially, Catie broadly defined the practice of explanation construction, but by the end of the plant unit, had developed a more refined understanding that was more closely aligned with the educative materials. Additionally, Catie believed that having students construct explanations was important for herself and her students, but she never connected the idea that this inquiry practice could help her students learn science content. Finally, unlike the animal unit, Catie began to adopt learning goals that aimed to help students develop both their conceptual understanding as well as their ability to build explanations. This dual emphasis was consistent with the educative materials. However, some of Catie’s learning goals in the plant unit still only emphasized the importance of having her students learn science content. Catie explained that having students form explanations is important but only when conducting experiments. Catie’s Practice & the Role of Explanations During the Plant Unit Enactment Having explored Catie’s espoused perspective, we now turn to her practice. First, we describe Catie’s main generalized instructional practices and how they relate to fostering students’ explanations. Second, we detail her specialized practices for giving priority to explanations. Finally, we conclude by describing how Catie assessed her students’ explanations and her reasoning for why students developed inaccurate explanations.

What generalized practices does Catie frequently employ in her science teaching, and how do they relate to fostering students’explanations?In analyzing the field notes and interview transcripts, two generalized instructional practices emerged as central to Catie’s science teaching: reading books and reviewing science concepts. Catie even engaged in these instructional practices during the plant unit, which did not specifically emphasize these practices. During the units, Catie used these practices to foster students’ understanding of science content but not their ability to build evidence-based explanations. These practices are discussed below.

During the plant unit, Catie incorporated a reading component that was not originally part of the educative materials. She read several trade books (fiction and non-fiction) to her students on a variety of topics, including seed dispersal, germination, and roots. She also had her students read about plants in their textbooks. Catie saw reading as a valuable component to the plant unit,

in addition to the hands-on activities. She said, “I think [the plant unit] went really well. There was enough experiment but there was also enough book reading” (Interview 3, 6/7/05).

Catie also frequently read to her students during the animal unit, as evidenced by classroom observations and interview transcripts. She read from the textbook, in addition to several trade books, to help her students learn about living/nonliving things, camouflage, habitats, and vertebrates/invertebrates. Catie mentioned, “We usually start by reading whatever's in the text because the stuff for animals in the text was really good” (Interview 1, 4/28/05).

In explaining why she uses text in her science instruction, Catie explained that reading helps her students develop an understanding of science concepts. For example, in the second interview (5/17/05), Catie explained, “I’ve read [the students] that one [book] about how a seed travels. I mean they love when I read the books to them because they really pick up on the information, the pictures and things.” In this passage and others, Catie explained that reading books is an effective method for helping her students learn about science, especially when the books are written in “kids’ language” and illustrated with pictures (Interview 1, 4/28/05).

The following passage about the Seed Parts lesson further illuminates this idea that Catie used books to help her students understand the science content. She said,

I’m not exactly sure if they understood the different [seed] parts and why it’s necessary.

We really talked at length about the seed coat and how it’s important for it to protect the seed. Like this embryo and food supply, I’m sure one of the books I have will have something in there about that we can read about. (Interview 2, 5/17/05)

Catie explained that many students failed to learn the names of the different seed parts and their functions from the lesson activity that had students dissect a seed. As a result, Catie wanted to find a book to share with her students because she felt confident that it would enable her students to obtain this understanding. Thus, Catie used text during both the plant and animal units to help students learn the science content. However, she did not use text to foster students’ explanations.

The use of repetition emerged as a second prominent practice during both the animal and plant units. Catie frequently used this instructional practice to review science concepts with her students. For example, on multiple days following the Seed Parts lesson, Catie reviewed the three parts of a seed—food supply, embryo, and seed coat—and their respective functions with her students. (The following transcripts of classroom discourse are drawn from the field notes and may not be an entirely comprehensive representation of the discussion that evolved.) Catie: Can anyone tell me what happened to the lima bean when we soaked it in water?

S1: The seed coat came off.

Catie: Okay, the seed coat fell off.

S2: It cracked open.

Catie: Okay, what else did we notice?

S3: The food supply.

Catie: And what else was inside? (Students offer their best guesses.)

S4: A word that starts with an E.

Catie: Yes, it does start with an E. (After more guessing, one student remembers.)

S5: Embryo.

Catie: What did I tell you that it is?

S5: It is the root.

Catie: Okay, part of it will turn into a root. It’s that baby what? (Students don’t remember.) It’s the baby plant, remember? So we are hoping that the seeds will shed their seed coats so we can see their embryos. (Field Notes, 5/19/05)

A few days later, a similar exchange was observed.

Catie: What did we notice in our experiment with the lima beans soaked in water?

S1: The seed coat fell off.

Catie: Okay, the seed coat came off.

S2: It got bigger.

Catie: The seed got bigger…

S3: They were more smooth.

Catie: The seeds felt smooth. What part of the plant was growing? What was that part

called?

S4: Embryo.

Catie: And what did I say the embryo was?

S5: The beginning of a new plant. (Field Notes, 5/23/05)

Like other review sessions, Catie provided students with the opportunity to learn the science content but not to practice building explanations.

The interview transcripts provide further evidence that Catie used review sessions primarily to help her students learn science concepts. For example, in the third interview, Catie clarified why she reviewed plant and root parts with her students—interestingly, concepts that were not part of the educative materials but instead from books she had read to her students.

It’s just that whole idea of repetition, repetition, repetition, like a flash card. If you see it enough times, if you hear it enough times, you’ll remember… It’s better for them to be inundated with it over multiple times. Like we went over the different parts of the plant today and what is this part of the root called and what's that part called. And more and more kids every time are able to tell me the parts and what their names are so more or less that is a very good indication to me of how many kids are getting it and how much more we need to review. (Interview 3, 6/7/05)

This passage shows that Catie used repetition to help her students learn key science ideas.

Reading books and reviewing science concepts were two main generalized instructional practices that emerged during the teaching of both the animal and plant units. These practices provided students with the opportunity to learn key scientific ideas but not to learn how to build explanations. Because these two practices played a frequent role in Catie’s science teaching—even during the plant unit which did not emphasize these practices as originally written—and facilitated students’ learning of science content, Catie’s classroom instruction tended to place a strong focus on helping students understand science concepts.

What specialized practices (if any) does Catie use for giving priority to explanations? Even though the educative materials included teacher learning supports for fostering explanations, it was uncertain whether Catie would engage her students in building explanations during the plant unit, especially since her main instructional practices tended to focus only on science content and her learning goals did not always include explanations. Analysis of the field notes, interview transcripts, and student artifacts revealed that Catie did engage her students in building scientific explanations throughout the plant unit. In doing so, three specialized practices for giving priority to explanations emerged. Catie used the questions in the student worksheets, whole class discussion, and general and specific prompts to scaffold her students’ explanation construction. These practices are described below.

Classroom observations revealed that unlike the animal unit, Catie provided opportunities for her second graders to build explanations during the plant unit. She engaged her students in developing both oral and/or written explanations during all of the lessons in the unit, as

advocated by the educative curriculum materials. She even had her students build explanations in the Seed Parts lesson and the Plant Investigation lesson, even though her stated learning goals for these lessons had only emphasized the science content.

To help her students use their observations in constructing scientific explanations, Catie participated in several specialized practices. First, for all but one lesson, Catie engaged her students in developing written explanations using the questions in the student worksheets. Catie described the usefulness of these explanation questions, saying

As far as the experiments go, that question, “What have you seen or done that makes you think this way?” does help them to think about what it was that we did so that they have a better explanation. That seemed to be a reoccurring thing and it gave them more practice in explaining their reasoning and by the time we were halfway through [the unit] they were more comfortable doing that it seemed, so that was a good reoccurring question that was in there. (Interview 3, 6/7/05)

Additionally, most students answered the explanation questions in the worksheets and at least one student in every lesson (often more) developed a complete, accurate explanation. Below are examples of student explanations (with sentence starters in brackets) developed during the unit.

[My seed depends on] animals and people [to move]. [I think my seed can move in this way because] I made it with sticks to make it stick to other things. (Student response from Seed Dispersal lesson, 5/12/05)

[Do plants need sunlight?] Yes. [I think this is the answer to my question because] the plants that did not get sunlight are crumbled. (Student response from Plant Investigation lesson, 5/26/05)

These student explanations show that Catie used the questions in the student worksheets to structure students’ explanation construction.

Second, in addition to helping students develop written explanations, Catie also provided opportunities for her students to communicate their explanations in whole class discussions. For example, at the end of some lessons, Catie had her students share their explanations as a class. She said, “We went through each question, and I read it to them and said, ‘Now put down your answer.’ We did all of the questions like that and then we went back and reviewed each of them separately again” (Interview 3, 6/7/05). Catie also added a whole class discussion to an activity that she had added to the Seed Dispersal lesson, which did not initially include an explanation component. This modification provided students with the opportunity to connect their observations of seeds to their claims about how they thought specific seeds traveled. This critical incident shows that Catie recognized that this activity was incomplete, thereby adding a discussion component to help her students make sense of the science. Thus, Catie not only used whole class discussions to help her students construct explanations but did so for an activity that was not initially designed with an explanation component.

Catie’s third specialized practice for giving priority to explanations entailed rephrasing the questions in the student worksheets by using general and specific prompts. With regard to general prompts, Catie often followed up explanation questions by asking students to use describing words and/or to explain their reasoning for the answers they gave. For example, as Catie walked her students through the questions in the Sunlight Investigation lesson, she reminded students to use reasoning to explain why they thought plants needed sunlight or not: “‘Do plants need sunlight?’ We want to write that down in number one. Don’t forget your capital and question mark…All right take a look at number two. ‘What do you think is the answer to your question?’ I want you to take a minute to think about the answer to the

作业━━第 1 章(2)━━运算符与表达式

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EL表达式语法介绍

1.1 EL表达式： EL表达式规定为：eval-expression和literal-expression,同时E L表达式支持Compositeexpressions,很多EL表达式（eval-ex pressions和literal-expressions）被聚合在一起。 EL表达式被解析成数值表达式和方法表达式。其中，取值表达式去引用一个值，而方法表达式则是关联一个方法。一旦被解析之后，表达式能够被优化地计算一次或多次。 下面我们来分为：eval-expression、literal-expression、Compo siteexpressions来讲述 1.1.1Eval-expression Eval-expression是以使用${expr}或者#{expr}结构的形式构成。两种方式都是相同的方式，能很好被解析和计算，尽管它们在使用时有着不同的意义从技术方面来说。 从J2EE层规范协定来说，${expr}结构是直接计算而#{expr}结构则是延期计算，这种界定符号指出了在J2EE层两种表达式类型的语义上面的区别。#{expr}这种界定符号被称为延迟计算是因为直到系统需要的时候才计算。而${expr}这种界

定符号则是在JSP页面编译的时候就计算，就是为什么叫做直接计算的原因。 1.1.1.1作为取值表达式的计算表达式 当解析成一个取值表达式的时候，eval-expression能被计算成左值和右值。若在EL中有等号操作符号出现，右值是类型出现在等号的右边的表达式，左值同理。 右值比如： 以下面这个例子为例：

CAD特殊符号代码大全

常见的快捷命令 （一）字母类 1、对象特性 ADC, *ADCENTER（设计中心“Ctrl＋2”） CH, MO *PROPERTIES(修改特性“Ctrl＋1”) MA, *MATCHPROP（属性匹配） ST, *STYLE（文字样式） COL, *COLOR（设置颜色） LA, *LAYER（图层操作） LT, *LINETYPE（线形） LTS, *LTSCALE（线形比例） LW, *LWEIGHT （线宽） UN, *UNITS（图形单位） ATT, *ATTDEF（属性定义） ATE, *ATTEDIT（编辑属性） BO, *BOUNDARY（边界创建，包括创建闭合多段线和面域） AL, *ALIGN（对齐） EXIT, *QUIT（退出） EXP, *EXPORT（输出其它格式文件）IMP, *IMPORT（输入文件） OP,PR *OPTIONS（自定义CAD设置）PRINT, *PLOT（打印） PU, *PURGE（清除垃圾） R, *REDRAW（重新生成） REN, *RENAME（重命名） SN, *SNAP（捕捉栅格） DS, *DSETTINGS（设置极轴追踪） OS, *OSNAP（设置捕捉模式） PRE, *PREVIEW（打印预览） TO, *TOOLBAR（工具栏） V, *VIEW（命名视图） AA, *AREA（面积） DI, *DIST（距离） LI, *LIST（显示图形数据信息） 2、绘图命令： PO, *POINT（点） L, *LINE（直线） XL, *XLINE（射线） PL, *PLINE（多段线） ML, *MLINE（多线） SPL, *SPLINE（样条曲线） POL, *POLYGON（正多边形） REC, *RECTANGLE（矩形） C, *CIRCLE(圆) A, *ARC(圆弧) DO, *DONUT（圆环） EL, *ELLIPSE（椭圆） REG, *REGION（面域） MT, *MTEXT（多行文本） T, *MTEXT（多行文本） B, *BLOCK（块定义） I, *INSERT（插入块） W, *WBLOCK（定义块文件） DIV, *DIVIDE（等分） H, *BHATCH（填充） 3、修改命令： CO, *COPY（复制） MI, *MIRROR（镜像） AR, *ARRAY（阵列） O, *OFFSET（偏移） RO, *ROTATE（旋转） M, *MOVE（移动） E, DEL键 *ERASE（删除） X, *EXPLODE（分解） TR, *TRIM（修剪） EX, *EXTEND（延伸） S, *STRETCH（拉伸） LEN, *LENGTHEN（直线拉长） SC, *SCALE（比例缩放） BR, *BREAK（打断） CHA, *CHAMFER(倒角) F, *FILLET（倒圆角） PE, *PEDIT（多段线编辑） ED, *DDEDIT（修改文本）

Linux Shell特殊字符和控制字符大全

Linux Shell特殊字符和控制字符大全Shell特殊字符 # 注释 ?表示注释 #注释 ?在引号中间和\#等表示#本身 ?echo ${PATH#*:} # 参数替换,不是一个注释 ?echo $(( 2#101011 )) # 数制转换,不是一个注释 ; 分隔 ?命令分隔，在一行中写多个命令 echo "aa" ; echo "bb" ?在条件中的if和then如果放在同一行，也用;分隔 ;; case条件的结束 . 命令相当于source命令 ?命令：source ?文件名的前缀，隐藏文件 ?目录：.当前目录，..父目录 ?正则表达式：匹配任意单个字符 "" 部分引用支持通配符扩展 ' ‘ 全引用，不进行通配符扩展 \ 转义 / 目录分隔符 , 多个命令都被执行，但返回最后一个 ` 后置引用 : 操作符 ?空操作 ?死循环： while : ?在if/then中表示什么都不做，引出分支

?设置默认参数： : ${username=`whoami`} ?变量替换： : ${HOSTNAME?} ${USER?} ${MAIL?} ?在和 > (重定向操作符)结合使用时,把一个文件截断到0 长度,没有修改它的权限；如果文件在之前并不存在,那么就创建它.如: : > data.xxx #文件"data.xxx"现在被清空了. 与 cat /dev/null >data.xxx 的作用相同然而,这不会产生一个新的进程,因为":"是一个内建命令. 在和>>重定向操作符结合使用时,将不会对想要附加的文件产生任何影 响. 如果文件不存在,将创建. * 匹配0个或多个字符；数学乘法；**幂运算 ? 匹配任意一个字符；但在((a>b?a:b))表示c语言中的三目运算 $ ?取变量的值 echo $PATH ?正则表达式中表示行的结尾 ?${} 参数替换 ${PAHT} ?$* 所有参数 ?$# 参数个数 ?$$ 进程的ID ?$? 进程的返回状态 ( ) ?命令组，在一个子Shell中运行 (a=3;echo $a) 其中定义的变量在后面不可用 ?数组初始化： array=(a,b,c) { } 代码块，即一个匿名函数，但其中定义的变量在后面依然可用 { } \; 用在find的-exec中 $find -name *.txt -exec cat {} \; [ ] ?测试 [-z $1] ?数组元素 a[1]='test' ?[[]]表示测试使用[[ ... ]]条件判断结构, 而不是[ ... ], 能够防止脚本中的许多逻辑错误. 比如, &&, ||, <, 和> 操作符能够正常存在于[[ ]]条件判断结构中, 但是如果出现在[ ]结构中的话, 会报错.

EL表达式

EL表达式总结 EL表达式总是用大括号括起，而且前面有一个美元符（$）前缀：${expression}。 表示式中第一个命名变量要么式一个隐式对象，要么是某个作用域（页面作用域、请求作用域、会话作用域或应用作用域）中的一个属性。 点号操作符允许你使用一个Map键或一个bean性质名来访问值，例如，使用${foo.bar}可以得到bar的值，在此，bar是Map foo的Map键名，或者是bean foo的一个性质。放在点号操作符右边的东西必须遵循Java的标识符命名规则！（换句话说，必须以一个字母、下划线或美元符开头，第一个字符后面可以有数字，但不能有其他字符）。 点号右边只能放合法的Java标识符。例如，${foo.1}键就不可以。 []操作符比点号功能更强大，因为利用[]可以访问数组和List，可以把包含命名变量的表达式放在中括号里，而且可以做任意层次的嵌套，只要你受得了。 例如，如果musicList是一个ArrayList，可以用${musicList[0]}或${musicList[“0”]}来访问列表的第一个值。EL并不关心列表索引加不加引号。 如果中括号里的内容没有用引号引起来，容器就会进行计算。如果确实放在引号里，而且不是一个数组或List的索引，容器就会把它看作是性质或键的直接命名。 除了一个EL隐式对象（PageContext）外，其他EL隐式对象都是Map。从这些隐式对象可以得到任意4个作用域中的属性、请求参数值、首部值、 cookie值和上下文初始化参数。非映射的隐式对象是pageContext，它是PageContext对象的一个引用。 不要把隐式EL作用域对象（属性的Map）与属性所绑定的对象混为一谈。换句话说，不要把requestScope隐式对象与具体的JSP隐式对象 request混淆。访问请求对象只有一条路，这就是通过pageContext隐式对象来访问（不过，想从请求得到的一些东西通过其他EL隐式对象也可以得到，包括param/paramValues、header/headerValues和cookie）。 EL允许你调用一个普通Java类中的公共静态方法。函数名不一定与具体的方法名相匹配！例如，${foo:roolIt()}并不意味着包含函数的类中肯定有一个名为roolIt()的方法。 使用一个TLD将函数名（例如roolIt()）映射到一个具体的静态方法。使用元素声明一个函数，包括函数的(roolIt())、完全限定类以及，其中包括返回类型以及方法名和参数表。 要在JSP中使用函数，必须使用taglib指令声明一个命名空间。在taglib指令中放一个prefix属性，告诉容器你要的函数在哪个TLD里能找到。例如：<%@ taglib prefix="mine" uri="/WEB-INF/foo.tld" %> 基本语法

CAD命令、特殊符号代码大全

常用命令： A——ARC——圆弧B——BLOCK——块定义C——CIRCLE——圆D——DIMSTYLE——标注样式E/DEL键——ERASE——删除F——FILIET——倒圆角H——BHATCH——填充L——LINE——直线 M/S——MOVE——移动O——OFFSET——偏移P——PAN——实时平移（图标为小手）X——EXPLODE——分解PO——POINT——点XL——XLINE——射线ML——MLINE——多线PL——PLINE——多段线POL——POLYGON——正多边形REC——RECTANGLE——矩形DO——DONUT——圆环EL——ELLIPSE——椭圆CO——COPY——复制MI——MIRROR——镜像AR——ARRAY——阵列RO——ROTATE——旋转TR——TRIM——修剪EX——EXTEND——延伸CHA——CHAMFER——倒角F——FILIET——倒圆角BR——BREAK——打断 尺寸标注： DLI——DIMLINEAR——直线标注DAL——DIMALIGNED——对齐标注DRA——DIMRADIUS——半径标注DDI——DIMDIAMETER——直径标注DAN——DIMANGULAR——角度标注DCE——DIMCENTER——中心标注DOR——DIMORDINATE——点标注TOL——TOLERANCE——标注形位公差LE——QLEADER——快速引出标注DBA——DIMBASELINE——基线标注DCO——DIMCONTINUE——连续标注DED——DIMEDIT——编辑标注DOV——DIMOVERRIDE——替换标注系统变量 常用CTRL快捷键： 【CTRL】＋1—PROPERTIES—修改特性【CTRL】＋2—ADCENTER—设计中心 【CTRL】＋O——OPEN——打开文件【CTRL】＋N/M——NEW——新建文件 【CTRL】＋P——PRINT——打印文件【CTRL】＋S——SAVE——

[java入门学习]第 3 章 运算符和表达式.

第 3 章运算符和表达式 运算符指明对操作数所进行的运算。按操作数的数目来分，可以有一元运算 符 (如 ++、--，二元运算符(如 +、＞和三元运算符 (如?:，它们分别对应于一个、两个和三个操作数。对于一元运算符来说 ,可以有前缀表达式 (如++i 和后缀表达式 (如 i++，对于二元运算符来说则采用中缀表达式(如a+b。按照运算符功能来分,基本的运算符有下面几类 : 1.算术运算符 (+,-,*,/,%,++,-- 2.关系运算符 (＞,＜,＞=,＜=,==,!= 3.布尔逻辑运算符 (!,&&,|| 4.位运算符 (＞＞,＜＜,＞＞＞,&,|,^,～ 5.赋值运算符 (=,及其扩展赋值运算符如+= 6.条件运算符 ( ?: 7.其它 (包括分量运算符·，下标运算符 [],实例运算符 instance of，内存分配运算符new，强制类型转换运算符(类型，方法调用运算符 ( 等 本章中我们主要讲述前6类运算符。 § 3.1算术运算符 算术运算符作用于整型或浮点型数据 ,完成算术运算。 一、二元算术运算符 如下表所示运算符用法描述 + op1+op2 加 - op1-op2 减 * op1*op2 乘 / op1/op2 除 % op1%op2 取模(求余

Java对加运算符进行了扩展,使它能够进行字符串的连接 ,如 "abc"+"de",得到 串 "abcde"。我们将在第七章中讲解。与C、 C++不同,对取模运算符%来说,其操作数可以为浮点数, 如 37.2%10=7.2。 二、一元算术运算符 如下表所示 : 运算符用法描述 + +op 正值 - -op 负值 ++ ++op,op++ 加1 -- --op,op-- 减1 i++与 ++i的区别 i++在使用i之后,使 i的值加 1,因此执行完 i++后,整个表达式的值为 i,而 i的值变为 i+1。 ++i在使用i之前,使 i的值加 1,因此执行完 ++i后 ,整个表达式和 i的值均为 i+1。 对 i--与 --i同样。 例 3.1.下面的例子说明了算术运算符的使用 public class ArithmaticOp{ public static void main( String args[] { int a=5+4; //a=9 int b=a*2; //b=18 int c=b/4; //c=4 int d=b-c; //d=14 int e=-d; //e=-14 int f=e%4; //f=-2 double g=18.4;

Word查找和替换通配符(完全版)

Word查找栏代码·通配符一览表 注：要查找已被定义为通配符的字符，该字符前键入反斜杠\ 。查找？、*、（、）、[ 、] 等的代码分别是\？、\*、\(、\)、\[、\] 。

Word替换栏代码·通配符一览表

Word通配符用法详解 1、任意单个字符： “?”可以代表任意单个字符，输入几个“?”就代表几个未知字符。如： 输入“? 国”就可以找到诸如“中国”、“美国”、“英国”等字符； 输入“???国”可以找到“孟加拉国”等字符。 2、任意多个字符： “*”可以代表任意多个字符。如： 输入“*国”就可以找到“中国”、“美国”、“孟加拉国”等字符。 3、指定字符之一： “[]”框内的字符可以是指定要查找的字符之一，如： 输入“[中美]国”就可以找到“中国”、“美国”。又如： 输入“th[iu]g”，就可查找到“thigh”和“thug”。 输入“[学硕博]士”，查找到的将会是学士、士、硕士、博士。 输入“[大中小]学”可以查找到“大学”、“中学”或“小学”，但不查找“求学”、“开学”等。 输入“[高矮]个”的话，Word查找工具就可以找到“高个”、“矮个”等内容。 4、指定范围内的任意单个字符： “[x-x]”可以指定某一范围内的任意单个字符，如： 输入“[a-e]ay”就可以找到“bay”、“day”等字符，要注意的是指定范围内的字符必须用升序。用升序。如： 输入“[a-c]mend”的话，Word查找工具就可以找到“amend”、“bmend”、“cmend”等字符内容。 5、排除指定范、排除指定范围内的任意单个字符： “[!x-x]”可以用来排除指定范围内的任意单个字符，如： 输入“[!c-f]”就可以找到“bay”、“gay”、“lay”等字符，但是不等字符，但是不会找到“cay”、“day”等字符。要注意范围必须用升序。

EL表达式与JSTL

EL和JSTL 主要内容 ?EL表达式 ?JSTL标签库

1.EL表达式 EL表达式又称为表达式语言（Expression Language），它是JSP中一个很重要的组成部分。在JSP页面中使用EL表达式，可以简化对变量和对象的访问。 EL表达式的语法非常的简单，所有的EL表达式都是以“${”开始，以“}”结束，比如${name}。EL表达式会将表达式中的结果在页面上输出，就像使用JSP的表达式结构或使用out内置对象进行输出一样。 EL表达式对运算符支持 使用EL表达式进行算术运算，在EL表达式中支持+、-、*、/、%运算，示例如下： 代码演示：EL表达式算术运算 <%@ page language="java" pageEncoding="UTF-8"%> 12 + 15 = ${12+15}
12 * 15 = ${12*15}
12 - 15 = ${12-15}
12 / 15 = ${12/15}
12 % 15 = ${12%15}

图1 EL表达式算术运算结果 在EL表达式中还可以支持关系运算符操作，示例如下： 代码演示：EL表达式关系运算符 12==15 ${12==15}
12<15 ${12<15}
12>15 ${12>15}
12<=15 ${12<=15}
12>=15 ${12>=15}
12!=15 ${12!=15} EL表达式除了支持普通的关系运算符外，还可以使用字符来表示关系运算符，下面的写法和上面使用普通关系运算符表示的顺序一一对应： 代码演示：EL表达式关系运算符 12==15 ${12 eq 15}
12<15 ${12 lt 15}
12>15 ${12 gt 15}
12<=15 ${12 le 15}
12>=15 ${12 ge 15}
12!=15 ${12 ne 15}

特殊符号

CAD字体特殊符号编码说明编码：代表： ％％091或中括号“[”：上标文字起始符 ％％093或中括号“]”：上标文字结束符 例如：m2＝m％％0912％％093或m[2] ％％123或大括号“{”：下标文字起始符 ％％125或大括号“}”：下标文字结束符 例如：m2＝m％％1232％％125或m{2} ％％130或感叹号“！”：一级钢符号 ％％131或符号“^”：二级钢符号 ％％132或美元符号“$”：三级钢符号 ％％133：四级钢符号 ％％134：特殊钢筋符号 ％％135：L型钢符号 ％％136：H型钢符号 ％％137：槽型钢符号 ％％138：工字钢符号 ％％139：文字缩小0.8倍 ％％140：文字放大1.25倍 ％％141：罗马数字Ⅰ ％％142：罗马数字Ⅱ ％％143：罗马数字Ⅲ ％％144：罗马数字Ⅳ ％％145：罗马数字Ⅴ ％％146：罗马数字Ⅵ ％％147：罗马数字Ⅶ ％％148：罗马数字Ⅷ ％％149：罗马数字Ⅸ ％％150：罗马数字Ⅹ ％％151：小于等于号≤ ％％152：大于等于号≥ ％％153：倒三角符号▽ ％％154：圆中有一个字符的特殊文字的开始％％155：圆中有一个字符的特殊文字的结束 例如：①可以写为％％1541％％155 ％％156：圆中有二个字符的特殊文字的开始％％157：圆中有二个字符的特殊文字的结束 例如：⑩可以写为％％15410％％155 ％％158：圆中有三个字符的特殊文字的开始％％159：圆中有三个字符的特殊文字的结束％％p：正负号± ％％u：字体加下划线的起始和结束 ％％c：直径符号 ％％o：字体加上划线的起始和结束 ％％d：度，温度符号 一 级 钢 二 级 钢 三 级 钢 四 级 钢 特 殊 钢 角 钢 宽 翼 钢 槽 钢 工 字 钢 小 于 等 于 大 于 等 于 倒 三 角 直 径 部分符号 示意图

运算符和表达式教案

QBASIC语言程序设计之 运算符和表达式 科目：计算机 授课人：赵华 时间：2007年10月

《运算符和表达式》教案 教学目标： 1、识记运算符的分类及表达式的定义。 2、掌握算术运算符的运算规则。 3、掌握QBASIC表达式的书写规则。 4、掌握算术表达式的求值方法。 教学重点： 1、掌握算术运算符的运算规则。 2、掌握算术表达式的求值方法。 教学难点： 1、掌握算术运算符的运算规则。 2、掌握算术表达式的求值方法。 课前巩固： 1、函数SQR（X）的功能是什么？（举例介绍） 2、函数INT（X）的功能是什么？（举例介绍） 教学内容： 一、运算符的分类 运算符表示对数据进行的具体运算。在QBASIC中分为四类：算术运算符、字符串运算符、关系运算符、逻辑运算符本节我们重点学习算术运算符和算术表达式的有关内容。 二、算术运算符 1、种类： 2、运算规则： ①^ 是乘方运算符： 例如：6^2就表示数学上的62，其值等于36。 2^-2就表示数学上的2-2，其值等于0.25。

② \ 是整除运算符： 运算功能是：如果参与运算的两个数是整数，运算结果为商的整数部分；如果参与运算的量含有小数，则系统先将它们按四舍五入转换为整数，然后再进行运算。 例1： 7 \ 2 = 3 10 \ 4 = 2 例2： 8.7 \ 5 = 1 12.37 \ 4.78 = 2 ③ MOD 是求余运算符： 运算功能是：如果参与运算的两个数是整数，运算结果为两数相除后的余数；如果参与运算的量含有小数，则系统先将它们按四舍五入转换为整数，然后相除取它们的余数。 例1： 12 MOD 5 = 2 23 MOD 4 = 3 例2： 11.7 MOD 8 = 4 13.23 MOD 4.76 = 3 三、算术表达式 1、什么叫表达式？ 是指用圆括号和运算符将常量、变量和函数连接起来的式子。 2 、表达式分为哪几类？ 根据运算性质不同可分为四类： 算术表达式 、 字符表达式 、 关系表达式 、 逻辑表达式 3、什么是算术表达式？ 就是用圆括号和算术运算符将数值常量、变量和函数连接起来的式子。 4、怎样把代数式写成QBASIC 的算术表达式 例1： 2X + Y +6 写成QBASIC 表达式为： 2*X +Y + 6 例2：A AC 24B +B -2-写成QBASIC 表达式为： （-B+SQR （B^2-4*A*C ））/(2*A) 例3： B A y x +写成QBASIC 表达式为： （ABS （X ）* ABS （Y ））/（A+ B ）

第3章表达式与运算符测试

C语言第3章《运算符与表达式》测试题 一、选择题(每题2分，共50分) 1、表达式“2，4，6，8”的值为（） A.2 B.4 C.6 D.8 2、以下程序的输出结果是（） main() {int a=12,b=0x12; printf(“%d%d\n”,--a,++b); } A.12 12 B.12 18 C.11 10 D.11 19 3、设x和y都是int型变量，则执行表达式“x=(y=4,z=16),k=32”后，x的值为（） A.4 B.16 C.32 D、52 4、设x为int型变量，执行语句“x=’A’;x*=2+2;”后，的值为（） A.65 B.260 C.132 D.语句错误 5、若有语句“int a=5;a++*2;”则表达式“a++*2”的值为（） A.7 B.12 C.5 D.10 6、设x和y为int型变量，表达式“x+=y;y=x-y;x-=y;”的功能是（） A.把x和y按从小到大排列 B.把x和y按从大到小排列 C.无确定结果 D.交换x和y的值 7、下面程序的输出结果是（） main() {int x=’\23’; printf(“%d\n”--x); } A.19 B.18 C.23 D.24 8、若变量f已定义为float型， i为int 型，则下面（）表达式（或语句）能够实现将f的数值保留小数点后两位，第3位进行四舍五入的运算。 A.f=(f*100+0.5)/100.0 B.i=f*100+0.5,f=i/100.0; C.f=(int)(f*100+0.5)/100 D.f=(f/100+0.5)*100.0 9、下面表达式正确的是（） A. a+b=5 B.56=a11 C.5.6+6.2%3.1 D.a=5,b=6,c=7 10、若t为double型变量，执行逗号表达式“t=(x=0,x+5),t++;”的输出结果是（）

WORD通配符全攻略

WORD通配符全攻略 (1) 通配符主要有 (2) word 查找的通配符高级篇 (7) Word查找替换高级用法五例 (9) Word查找栏代码?通配符一览表 (10) Word查找栏代码?通配符示例 (12) Word替换栏代码?通配符一览表 (12) Word查找与替换.ASCII字符集代码 (13) Word中通配符用法全攻略！ (14) WORD通配符全攻略 作者：逍遥赵2006-01-17 11:44分类：默认分类标签： 什么是WORD通配符？通配符是配合WORD查找、替换文档内容的有利武器。打开WORD，按CTRL+F，点击“高级”，勾选“使用通配符”，再点击“特殊字符”，就看到以下通配符： 1、“>”：使用该通配符的话，可以用来指定要查找对象的结尾字符串，比方说要是大家记不清所要查找对象的完整内容了，但记得要查找对象的结尾字符串是某个特定的字符，此时大家就可以用“>”来将这个特定字符表达出来，这样word程序就自动去查找以这个特定字符结尾的相关内容了。 实例一：输入“en>”的话，word程序就会在当前文档中查找到以“en”结尾的所有目标对象，例如可能找到“ten”、“pen”、“men”等等。 实例二：在查找对话框中输入“up>”的话，Word查找工具就会在当前文档中查找到以“up”结尾的所有目标对象，例如会找到“setup”、“cup”等等对象。 实例三：如果查找的是汉字目标，我们要注意的是，查找的汉字应该是结尾字词（后面应该有标点符号分隔）。 2、“<”：它与“>”正好是相对的一组通配符，所以，我们可以用它来查找以某字母开头的对象。 实例：输入“

运算符和表达式

关系运算符和关系表达式导学案 班级：姓名： 6学习目标： 1.了解关系运算和关系表达式的概念，掌握关系运算符的功能、优先级、结合性，学会正确书写和计算关系表达式的值。 2.了解逻辑运算和关系表达式的概念，掌握逻辑运算符的功能、优先级、结合性，学会正确书写和计算逻辑表达式的值。 学习重点： 关系运算符和逻辑运算符的优先级和结合性、关系表达式和逻辑表达式值的计算。 【课前预习】 1.C语言提供了一组关系运算符，其基本信息如图所示，用来比较两个运算对象之间的关系。 运算符名称分类优先级结合性< <= > >= == != 2.C语言提供了3种逻辑运算符，其基本信息如图所示。 运算符名称分类优先级结合性！ && || 【新课讲解】 任务一：关系运算符和关系表达式 一、关系运算的概念： 二、关系运算符及其优先次序： 1.运算符种类： 2.优先次序：

3.结合性： 三、关系表达式 1.概念： 2.一般形式： 3.关系表达式的值： 任务二：逻辑运算符和逻辑表达式 一、逻辑运算的概念： 二、逻辑运算符及其优先次序： 1.运算符： 2.真值表： a b !a !b a&&b a||b 真真 真假 假真 假假 结论： 3.优先次序： 4.结合性： 三、逻辑表达式 1.概念： 2.逻辑表达式的值： 3.说明：

【巩固练习】 1.假设有三条边a、b、c，写出它们能构成三角形的逻辑表达式。 2.已定义“char ch='$';”、“int i=1,j;”，执行j=!ch&&i++以后，i的值为__。 3.一个数既能被3整除又能被5整除的表达式。 4.如果a=3,b=2,c=1，那么a>bb&&bc 的值为______。 5.C语言中复合逻辑表达式中所包含的所有运算都将会被执行。（） 6.当数值型数据作为逻辑运算的操作数时，只有1才被当做是“真”，0当做“假”，其余的数值均为非法的。（） 7.数值型数据不能当做逻辑量参与逻辑运算。（） 8.在C语言中表示数学中的a的范围的表达式-10≤a≤10的C语言表达式为 -10<=a<=10。（） 9.判断char型变量c1是否为小写字母的最简单且正确的表达式为（） A.‘a’<=c1<=’z’ B.(c1>’a’)&&(c1<’z’) C.(c1-20>=’A’)&&(c1-21<=’Z’) D.(c1>=’a’)&&(c1<=’z’)

EL表达式

EL: 简介： (Expression Language.) 作用：EL表达式存取变量数据。方便使用。 语法结构: ${ ……. } EL运算符： .与[] EL提供了.和[] 两个运算符存取数据 假设session变量为user的javaBean，有一个name属性，取值为${https://www.wendangku.net/doc/d213062141.html,} 或者${https://www.wendangku.net/doc/d213062141.html,er[“name”]} 算术运算符 有五个：+、-、*或$、/或dive、%或mod ${2+3} ${2/3}或${2 div 3} ${2%3}或${2 mod 3} 关系运算符 有六个：==或eq、!=或ne、<或lt、>或gt、<=或le、>=或ge ${5==5} ${5 eq 5} ${5 != 5} ${5 ne 5} 逻辑运算符 有三个：&&或and、||或or、!或not

${A &&B} ${A and B} ${A || B} ${!A} ${not A} 其它运算符 有三个：Empty运算符、条件运算符、()运算符 ${empty https://www.wendangku.net/doc/d213062141.html,} ${3+9 } ${5==5 } ${empty a } EL隐式对象： 1、与范围有关的隐式对象。 ●pageScope使用范围：当前页面 ●requestScope使用范围：当前请求 ●sessionScope使用范围：当前会话 ●applicationScope使用范围：服务器启动到结束 例子： <% pageContext.setAttribute("key","b"); request.setAttribute("key","c"); session.setAttribute("key","d"); application.setAttribute("key","e"); %> ${key } ${requestScope.key } ${sessionScope.key }

五笔加加特殊符号编码列表

五笔加加特殊符号编码列表 符号名称编码符号名称编码空格pwst ‖双竖线cjxg 双空格cpst 〖〗空心括号pnrk ，逗号gkkg 【】实心括号pnrk 、顿号gbkg √ 对勾cfqc 。句号qkkg ≈ 约等于xtgf ·圆点lkhk ≤ 小于等于igtg ·间隔号ubkg ≥ 大于等于dgtg ——破折号drkg ＜小于uggf ～波浪号iikg ＞大于ddgf …… 省略号itkg ′ 单撇号urkg …? 单引号uxkg 〃双撇号crkg “” 双引号cxkg ′ 分wv 〔〕方括号yrkg 〃秒ti 〈〉单书名号unqk ♂ 雄性符号dntk 《》书名号nqkg ♀ 雌性符号hntk 『』竖书名号jnqk °度ya ±正负号gqkg ℃摄氏度rqya ∶对比号cxkg ℃温标ijsf ‰ 千分号twkg §章节号uakg ％百分号dwkg ※花叉号ackg

（）圆括号lrkg π 圆周率lmyx ｛｝大括号drkg № 序号yckg ？问号ukkg ☆★五角星gqga ；分号wvkg ○ 圆圈lklu ：冒号jhkg ● 实心圆圈pnll ！叹号kckg ◇菱形afga ＃井号fjkg ◆实心菱形pnag ＄美元ugfq □ 矩形tdga ?英镑amqu ■ 实心矩形pntg ￥人民币wntm △三角形dqga ／斜杠wtsa ▲ 实心三角pndq 五笔加加系列符号编码列表 名称编码系列符号 大写罗马dplc ⅠⅡⅢⅣⅤⅥⅦⅧⅨⅩⅪⅫ 小写罗马iplc ⅰⅱⅲⅳⅴⅵⅶⅷⅸⅹ 大写希腊dpqe ΑΒΓΓΔΕΖΘΗΚ∧ΜΝΞΟ∏Ρ∑ΤΥΦΦΧΨ 小写希腊ipqe αβγδεδεζηθικλμνπξζηυθχψω 大写俄文dpwy АБВГДЕЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ Ё 小写俄文ipwy абвгдежзийклмнопрстуфхцчшщъыьэюя ?

Word 查找替换,通配符一览表

Word查找替换详细用法及通配符一览表 使用通配符 要查找“?”或者“*”，可输入“\?”和“\*”，\1\2\3依次匹配数对括号内容 查找(a)12(b) 替换\2XY\1 结果：bXYa ([.0-9]@) [MG]B 匹配文件大小，例1: 201 MB ,例2: 2.51 GB <(e*r)> 匹配“ enter ”，不配“ entertain ”。 主要有： 任意单个字符 ? 任意数字（单个）[0-9]或带小数点数字[.0-9] 任意英文字母 [a-zA-Z]或全小写[a-z] 指定范围外任意单个字符 [!x-z] 任意字符串 * 1个以上前一字符或表达式 @ n个以上前一字符或表达式 { n, } 制表符 ^t 不间断空格 ^s 段落标记 ^13 手动换行符 ^l or ^11 表达式 ( ) 单词开头,结尾 < >

[ 、] 等的代码分别是\?、\*、\(、\)、\[、\] 。

1、要查找已被定义为通配符的字符，那么需要在该字符前输入反斜杠(\)。 例如：要查找“?”或者“*”，可输入“\?”和“\*”。 2、如果使用了通配符，在查找文字时会大小写敏感。如果希望查找大写和小写字母的任意组合，那么请使用方括号通配符。 例如：输入“[Hh]*[Tt]”可找到“heat”、“Hat” 或“HAT”，而用“H*t”就找不到“heat”。 3、使用通配符时，Word只查找整个单词。例如，搜索“e*r ”可找到“enter”，但不会找到“entertain”。如果要查找单词的所有形式，需要使用适当的通配符字符。 例如：输入“<(e*r)”可找到“enter”和“entertain”。 4、选中“使用通配符”复选框后，也可查找脚注和尾注、域、段落标记、分节符和人工分页符及空白区域。只要在“查找内容”框中键入替代代码即可。 5、如果包含可选连字符代码，Word 只会找到在指定位置带有可选连字符的文字。如果省略可选连字符代码，Word 将找到所有匹配的文字，包括带有可选连字符的文字。 6、如果要查找域，必需显示域代码。要在显示域代码和域结果之间切换，请单击该域，然后按Shift+F9 组合键。要显示或隐藏文档中所有的域代码，请按Alt+F9 组合键。 7、在查找图形时，Word 只查找嵌入图形，而不能查找浮动图形。在默认情况下，Word 会将导入的图形以嵌入图形的方式插入到文档中。

keil C 运算符和表达式

运算符和表达式 运算符就是完成某种特定运算的符号。运算符按其表达式中与运算符的关系可分为单目运算符，双目运算符和三目运算符。单目就是指需要有一个运算对象，双目就要求有两个运算对象，三目则要三个运算对象。表达式则是由运算及运算对象所组成的具有特定含义的式子。C 是一种表达式语言，表达式后面加“；”号就构成了一个表达式语句。 赋值运算符 对于“=”这个符号大家不会陌生的，在 C 中它的功能是给变量赋值，称之为赋值运算符。它的作用就是把数据赋给变量。如，x=10；由此可见利用赋值运算符将一个变量与一个表达式连接起来的式子为赋值表达式，在表达式后面加“；”便构成了赋值语句。使用“=”的赋值语句格式如下： 变量 = 表达式； 示例如下 a = 0xFF; //将常数十六进制数 FF 赋于变量 a b = c = 33; //同时赋值给变量 b,c d = e; //将变量 e 的值赋于变量 d f = a+b; //将变量 a+b的值赋于变量 f 由上面的例子可以知道赋值语句的意义就是先计算出“=”右边的表达式的值，然后将得到的值赋给左边的变量。 算术，增减量运算符 对于 a+b,a/b 这样的表达式大家都很熟悉，用在 C语言中，+，/，就是算术运算符。C51的算术运算符有如下几个，其中只有取正值和取负值运算符是单目运算符，其它则都是双运算符： + 加或取正值运算符 - 减或取负值运算符 * 乘运算符 / 除运算符 % 取余运算符 算术表达式的形式： 表达式 1 算术运算符表达式 2 如：a+b*(10-a), (x+9)/(y-a) 除法运算符和一般的算术运算规则有所不同，如是两浮点数相除，其结果为浮点数，如 10.0/20.0 所得值为 0.5，而两个整数相除时，所得值就是整数，如 7/3，值为 2。像别的语言一样 C 的运算符与有优先级和结合性，同样可用用括号“（）”来改变优先级。这些和我们小时候学的数学几乎是一样的，也不必过多的说明了。 ++ 增量运算符 -- 减量运算符 这两个运算符是 C 语言中特有的一种运算符。在 VB，PASCAL 等都是没有的。作用就是对运算对象作加 1 和减1 运算。要注意的是运算对象在符号前或后，其含义都是不同的，虽然同是加1或减 1。如：I++，++I，I--，--I。 I++（或 I--）是先使用 I 的值，再执行 I+1（或 I-1） ++I（或--I）是先执行 I+1（或I-1），再使用I 的值。 增减量运算符只允许用于变量的运算中，不能用于常数或表达式。 关系运算符 对于关系运算符，在C中有六种关系运算符： ＞大于 ＜小于 ＞＝大于等于 ＜＝小于等于 ＝＝等于