Academic journal article Science and Children

The Benefits of Scientific Modeling: Constructing, Using, Evaluating, and Revising Scientific Models Helps Students Advance Their Scientific Ideas, Learn to Think Critically, and Understand the Nature of Science

Academic journal article Science and Children

The Benefits of Scientific Modeling: Constructing, Using, Evaluating, and Revising Scientific Models Helps Students Advance Their Scientific Ideas, Learn to Think Critically, and Understand the Nature of Science

Article excerpt

Have you ever wondered why we construct scientific models? Most likely, you've seen your share of volcanic eruptions made from vinegar and baking soda at elementary science fairs, asked students to make solar system mobiles, or perhaps asked students to represent the parts of a butterfly life cycle with different kinds of pasta. Are these scientific models? Do they help students develop their scientific ideas, think critically, and understand the nature of science?

A scientific model is a representation of a system that includes important parts of that system (along with rules and relationships of those parts) to help us think about and test ideas of the phenomena. Some familiar examples of scientific models include the particle model of matter, a light ray model, the water cycle, and a food web model that shows interactions between organisms. Models can be physical--such as the atom model--or conceptual, such as the water cycle model.

When considering the volcano and the butterfly pasta models mentioned earlier, we see that they cannot easily be used as scientific models, since they do not accurately predict or explain the phenomenon of volcanic activity or the cyclical nature of the butterfly life cycle. They represent an idea but they do not allow us to test an idea or extend it. The solar system model describes the order and type of planets in our solar system, so it is helpful for understanding these components, though the model is limited in the sense that it does not always accurately represent other aspects such as the motion around the Sun and the distances between planets.

Even better than knowing about powerful models is knowing and doing scientific modeling. What we mean by modeling is the experience of constructing, using, evaluating, and revising scientific models and knowing what guides and motivates their use. When students are engaged in scientific modeling, they are able to notice patterns and develop and revise representations that become useful models to predict and explain--making their own scientific knowledge stronger, helping them think critically, and helping them know more about the nature of science.

To demonstrate this, we describe a four- to six-week unit on evaporation and condensation for fifth-grade students that incorporates four essential aspects of scientific modeling. In the unit, students experience various kinds of scientific modeling as they construct, use, evaluate, and revise evaporation and condensation models to understand how a solar still (a device used to distill water using the Sun as a heat source) cleans dirty water.

Initial Explorations

To begin, in advance, the teacher prepares a solar still from a two-liter bottle and other supplies. To assemble the still, cut off the top of a two-liter soda bottle. Cut a narrow slit in each side of the bottle, and insert a large craft stick across the bottle through the slits. The craft stick provides a platform for the cap that collects the evaporated and condensed water. Tape the collection cap to the craft stick to prevent it from falling into the "dirty" water (water with soil or coffee grounds mixed in). Pour approximately one cup (250 mL) dirty water into the bottle. Cover the bottle with plastic wrap and secure it with a rubber band. Finally, place a weight (such as a metal marble) in the center of the plastic wrap, which helps the plastic wrap slope toward the collection cap in the bottle. (For best results, place the still in a warm place or use hot water.)

After about a week, evaporated and condensed water will have collected in the bottle cap, at which point the teacher presents the solar still to students. As the teacher presents the still, she asks students to make observations and to answer the questions, "Would you drink the liquid in the bottle cap?" and "Do you know what that liquid is and how it got there?" Most students don't know how the water got there and are hesitant to commit to an answer, so the teacher explains that over the next few days they will be doing more explorations to find out how the clear liquid got in the bottle cap. …

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