Using Pre-Built STELLA® Models in High School Physics

Dave Hamilton

Portland Public Schools and a Waters Foundation Systems Thinking/Dynamic Modeling Coach

Dynamic computer models can serve a variety of instructional purposes in K-12 classrooms. Involving students in the actual creation of a model is a powerful and valuable tool for teaching content in many disciplines. However, when students do not already know how to build and exercise computer models, content teachers may not think the value of the modeling experience outweighs the time investment necessary. Also, the cognitive load of learning the modeling process and the content at the same time may significantly diminish the value of model building. Fortunately, pre-built models or simulations can be designed to produce desired learning related to understanding of content as well as the development of thinking skills and long-term habits of mind.

An example of utilizing a content-driven simulation is a set of lessons developed on Newton's Second Law. The lessons include two dynamic models (one involving the throwing of a ball, the other sky diving) that focus on the concept of net force in determining the acceleration of objects in free fall. This concept is deceptively difficult for many students resulting in widely studied misunderstandings such as the "motion implies force" misconception.

Using the interface level of STELLA, the models are presented to students piece-by-piece. As they unfurl the models, the students are asked to predict the behavior of the system with a single force acting, then with multiple forces acting, and so on. They are also asked to predict how new features of the model will be added and to develop and test hypotheses. Instant feedback, such as the results of different experiments, encourages metacognition and helps students to adjust their thinking throughout the lesson.

The graphical nature of dynamic models facilitates learning of the lesson content even for students who have not previously used STELLA for modeling. The students are exposed to visual representations of relationships through the stock/flow diagram as well as the graphs and tables produced. The stock/flow diagram illustrates the fact that acceleration, a flow, varies as the net force varies, and becomes zero as soon as the net force becomes zero. Velocity, on the other hand, is a stock. Once the acceleration stops, the velocity remains unchanged.

In his book Visual Tools for Constructing Knowledge, David Hyerle emphasizes the crucial relationship between visual tools and learning, as well as the impact of technology and visual design, ".one of the exciting qualities of the computer is that it may be used as a metacognitive tool, an electronic reflecting pool for the mind." STELLA software enables teachers to create computer models related to a wide variety of topics at all levels of K-12 education. The instructional strategies accompanying the manipulation of pre-built models must be carefully planned. Student tasks that demand skillful thinking are essential to producing results such as metacognition, analysis, hypothesizing, and other types of thinking skills.

The lesson plan described above and the accompanying models are available on the Waters Foundation Website, www.watersfoundation.org.