Secondary Students' Dynamic Modeling Processes: Analyzing,Reasoning About,Synthesizing, and Testing Models of Stream Ecosystems

In this paper, we explore dynamic modeling as an opportunity for students to think about the science content they are learning. We examined the Cognitive Strategies for Modeling (CSMs) in which students engaged as they created dynamic models. We audio- and videotape-recorded eight pairs of ninth grade science students and analyzed their conversations and actions. In analyzing appropriate objects and factors for their model, some students merely enumerated potential factors whereas others engaged in rich, substantial, mindful analysis. In reasoning about their models, students discussed relationships in depth, concentrated only on the most important key relationships, or encountered difficulty distinguishing between causal and correlational relationships. In synthesizing working models, students mapped their model to aid visualization, focused on their goal, or talked about their model's appearance or form. Students attempted to articulate explanations for their relationships, but sometimes their explanations were shallow. In testing their models, some students tested thoroughly but only a few persisted in debugging their model's behavior so that it matched their expectations. In our conclusion we suggest that creating dynamic models has great potential for use in classrooms to engage students in thought about science content, particularly in those thinking strategies best fostered by dynamic modeling: analysis, relational reasoning, synthesis, testing and debugging, and making explanations.     

WHEN PUBLIC SERVICE RENDERS PERSONAL CHANGE: PORTRAITS OF SIX AVOCATIONAL TEACHERS

This paper presents portraits of six parents who became actively involved as avocational teachers in their synagogue's religious school. Based on two in‐depth interviews, the portraits trace avocational teachers' public commitment to the school and personal renewal as Jews. The portraits provide us with a closer look at the powerful impact that teaching and learning had on participants' views of themselves and their relationship to Jewish texts.     

Motivating Project-Based Learning: Sustaining the Doing,Supporting the Learning

Project-based learning is a comprehensive approach to classroom teaching and learning that is designed to engage students in investigation of authentic problems. In this article, we present an argument for why projects have the potential to help people learn; indicate factors in project design that affect motivation and thought; examine difficulties that students and teachers may encounter with projects; and describe how technology can support students and teachers as they work on projects, so that motivation and thought are sustained.     

Scoring Constructed Responses Using Expert Systems

The use of constructed-response items in large scale standardized testing has been hampered by the costs and difficulties associated with obtaining reliable scores. The advent of expert systems may signal the eventual removal of this impediment. This study investigated the accuracy with which expert systems could score a new, nonmultiple-choice item type. The item type presents a faulty solution to a computer programming problem and asks the student to correct the solution. This item type was administered to a sample of high school seniors enrolled in an Advanced Placement course in Computer Science who also took the Advanced Placement Computer Science (APCS) examination. Results indicated that the expert systems were able to produce scores for between 82% and 95% of the solutions encountered and to display high agreement with a human reader on the correctness of the solutions. Diagnoses of the specific errors produced by students were less accurate. Correlations with scores on the objective and free-response sections of the APCS examination were moderate. Implications for additional research and for testing practice are offered.