# II Creative Reasoning Processes to Support Model Modification

These are ways to support student reasoning while they are modifying a model.

There are many Level I strategies that can help support these processes; a few are listed at the bottom of this page.

Request that students add or subtract model elements to a model undergoing modification.

 Example 1 In a class where students were learning about the structure of the throat, after much discussion, the students had agreed on a model where the nose and mouth connect in a single tube, and then farther down that tube branches into two tubes, one to the lungs and another to the stomach. However, their model was still missing an important element the teacher wanted them to consider. The students had already agreed that food does not go into the lungs. Now the teacher asked, “What is going to prevent the food from going down to your lungs?” The students speculated that there had to be a muscle, or something like a sliding door or a trap door. The teacher’s question can be interpreted as a request for a new model element, and the students interpreted it that way, immediately giving a variety of suggestions for what that new element might be like. Example 2 A small group had drawn a model of the lungs that had a hole at the bottom for air to get to the body. T: You have this [hole in lung] that ll the air can sink out of; what do you want to do about that? Example 3 Students were constructing a model of charge flow and resistance within a circuit. T: Can anybody think of a way to make the model better, to account for our finding that not all bulbs light with the same brightness? Example 4 In this example, the teacher supplies a new element for the students’ mostly hollow models of the lungs (as in Example 2). T: Lungs are not hollow; they’re filled with tissue and little air cavities. The teacher then showed a slide of the structure of a lung. This supplied the idea that lungs are not hollow, but students still had a lot of elements to supply to reach the target model.  This was actually part of a long model-improvement cycle; see the sequence of images on our home page for part of it. Image from Energy in the Human Body: A Middle School Life Science Curriculum, by Rea-Ramirez, Nunez-Oviedo, and Clement (2004).

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Extreme Case Reasoning to Support Modification

Engage students in extreme case reasoning to to trigger ideas for improving the model.

Discussion is about the effects of setting an extremely high or low value for some variable in the system to trigger ideas for improving the model.

 Example 5 An example comes from a high school class in which students were discussing sources of resistance to current flow in a circuit with a battery and a bulb. Students agreed that the light bulb offered resistance but most had the impression that the wires did not. (Although the resistance of the wires is small, it is not zero.) The instructor asked whether, if the wires extended to a bulb on the moon and back, they would offer resistance--and many of the student thought that in that case they would. This helped them see that there could be some very tiny resistance from the wires in a normal circuit.

Using Analogies to Support Modification

Six classroom examples.

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Supporting and Contributing Strategies

Extreme Case Reasoning and Using Analogies can involve mental animation. There are a number of visualization strategies teachers can use to help with this. See:

Different Participation Strategies may be needed at this point in the lesson.

Articles and Websites

More in-depth discussion and more student examples are found in the following papers by our team:

Generating, evaluating, and modifying scientific models using projected computer simulations (Price & Clement, 2014)

Documenting the use of expert scientific reasoning processes by high school physics students (Stephens & Clement, 2010)