Goals

Research goals
This module is designed as a research tool. The goal of the research is two fold: 1) to learn about the conceptual framework students use to explain atomic scale phenomenon; and 2) to assess the effectiveness of Molecular Workbench by evaluating students reasoning with these models about phenomenon they have not been taught..

Learning Goals:
The module is focused on matter in its various states and the molecular properties of these states. Students will be asked to reason using the kinetic molecular theory. The power of the kinetic molecular theory in understanding the states of matter lies in helping students understand the molecules themselves do not change during physical changes in substances such as melting; instead, the changes reflect different arrangements and motions of the molecules.

The following,then, are the goals for the mini-module:

The central goal of this module is to research whether these tools help students identify and describe matter in its various states (solid, liquid, and gas) and to understand the molecular aspects of these states.

The second goal is determine whether the tools in this module help students explain observable phenomena and observable properties of matter in terms of the arrangement and motion of molecules.

 

Prior Knowledge and Naïve Conceptions
Many students in the middle school are familiar with the terms atoms and molecules. Some are even familiar with the concept that matter is made of particles. However, research on the topic of kinetic molecular theory has shown that students entering middle school have a great many alternative ideas about what the world is made of. Researchers from the Institute for Research on Teaching at Michigan State University have outlined and summarized the following ideas regarding middle school students conceptions of matter and the kinetic molecular theory:

With regard to the concept "Matter is anything that has weight and takes up space," students believe that air and other gases that are invisible are weightless, and that heat and light take up space.
Many students know that atoms and molecules exist and that matter is made of tiny particles. They have, however, many questions about this topic such as: How tiny are molecules? Is there air between molecules? Are all molecules moving? Even in solids? Is there just one type of molecule or are there many molecules?
Many students assume that there is a fairly simple relationship between the properties of a substance and the properties of its molecules. For example, they may believe that ice is made of cold, hard molecules, and that ice melts because the molecules become warmer and turn into liquid.

Various studies show that most middle school students will use particulate ideas in describing states of matter, especially when they are prompted to do so. A number of ways these ideas are used can be identified including: lack of appreciation of particle motion or of cohesive forces between particles in a solid; a tendency to associate increased separation of particles with increases in temperature; and, perhaps most significant of all, a tendency to attribute bulk properties to the particles themselves. The interplay between the action of cohesive forces on the one hand and particle motion and energy on the other hand is evident in very few students thinking.

Our goal is to help students address their alternate ways of thinking and begin a complex learning process that will allow them to incorporate unfamiliar ideas that are more scientifically accurate.

About Models
This module makes use of atomic level models. The activities in the unit are organized around the development of specific science concepts but simultaneously students can be asked to analyze the models they are learning from. Students should learn that models are tools and that they must be wrong in some respects or else it would be the thing itself. The trick is to see-with the help of a teacher-where it is right.

Unlike most models students think of (small versions of visible things), chemistry's tangible models are large metaphors for small, invisible things. Take, for example, a ball-and-stick model. To a chemist a molecule doesn't look like this model. Rather the model expresses our insight into the nature of the molecule. Joining the sticks and balls helps us visualize and learn about that molecule.

In this module students do not have to construct their own models.

Students will:

run a model and analyze its reasonability and fidelity by comparing model outputs to a target phenomena;
understand the behavior of a model by varying parameters, testing limits, and examining the interrelationships between variables;
apply model-based reasoning by grappling with a variety of explanations and phenomena.

In understanding the models students will need to reason using the key scientific concepts from this unit. It is our belief that students will gain a greater understanding of the concepts they will be studying and a facility with creating and understanding their own models as a result of these activities.

Investigative Questions
Located in the Activity Design and Execution section of each activity in an investigative question. It is this question that frames the learning goals and experiments for each activity. You may want to write the question on the board at the beginning of each session, point it out to the class, then return to the question at the end of each session and discuss how their experiences may have helped answer the question. Or you might have students write their thoughts as homework.