Assessing the Evolution in Model Construction in Sixth Grade: Drawing Versus Written Explanation

• In Event: Roundtable Session 2
  In Roundtable Session: Connections Between Drawings and Written Text in Student-Generated Particle Model Realizations

Abstract

1. Objectives
The particle model of matter is a building block for students’ understanding of more concepts, such as states of matter, phase changes, and chemical reactions . Modeling is one approach for supporting student development of a particle view of matter. Moreover, teachers need to recognize how student ideas develop over time in order to support student development of a particle view of matter. This study examines the evolution of the level of sophistication of students’ drawings and written explanations using the particle model of matter.
2. Methods of inquiry
The study describes student learning in the 6th grade chemistry unit ”How can I smell things from a distance?” The unit includes activities at specific points in which students create models of the same phenomenon in drawings and written explanations. During an eight-week implementation of the unit, three similar embedded assessments were collected from 122 students taught by three teachers from three different public schools in the United States. These sites were chosen based on teacher’s voluntary participation.
4. Sources of Data
Worksheets with two written response items were collected from students at the beginning, middle and end of the unit. Here. We focus on the first of these written response items that deals with students explaining in which room, a cold room or a warm room, they would smell an odor from an air freshener faster.
We identified four levels of student models, ranging from least sophisticated (“Descriptive”) to most sophisticated (“Complete”). A “Descriptive” drawing represents a macroscopic view of matter and the explanation represents a qualitative description of phenomena. At the “Mixed” level, students blend both aspects of a particle model and a descriptive model. Students at the “Basic” level can draw and describe matter at a particle level, but have difficulties in explaining movement or arrangement of particles at different states. Students at the “Complete” level draw and describe phenomena using a particle model and can explain states of matter, phase changes, and differences in properties of substances using this model. For example, Figure 1 illustrates a drawing and explanation that were both coded as “Descriptive” because it portrays merely macroscopic features and no particle ones. The relationship between student drawings and explanations was investigated by coding them into the three categories:
A. Drawing more sophisticated than explanation,
B. Drawing and explanation on the same level
C. Explanation more sophisticated than drawing.
4. Results
At the pretest, 52.5% of students’ explanations were at the same level as their drawing. At the middle of the unit, almost all students (91.8%) had drawings that were more sophisticated than their explanation. By the end of the unit, this percentage has decreased as 51.6% of students’ drawings are at a higher level of the scoring guide than their explanation.
5. Scholarly significance
This research shows that pictorial representations of the particle model are important for assessing progress in conceptual understanding. The comparison of written and pictorial models shows that students arrive at a more sophisticated level of knowledge, earlier than could be inferred from written explanations.

Author

• Joi Merritt, Arizona State Univeristy