IV Classroom Modes: Model Competition

The goal of classroom activity is to decide between competing models and select one to take forward for further improvement.

Model Competition is a kind of classroom mode that can occur when there is more than one candidate model under discussion and students engage in repeated rounds of a single Level III modeling phase: Evaluating a Model. This classroom mode can happen spontaneously or be planned by the teacher.

Indications that a session of Model Competition might be a useful next step in an instructional sequence are when a classroom discussion shows a strong difference of opinion about which model is the best one, with opposing “camps” among the students. When this occurs, we have seen teachers alter the next day’s lesson plan to take advantage of this opportunity, engaging their class in in-depth discussion and evaluation of the competing models.

A photograph of the teacher, Mr. N, shows him standing in front of a blackboard with two models of the lungs and heart drawn on the board. He is pointing to one of them. The diagrams cannot be clearly seen but are duplicated in the next two figures.Example 1

After his students had generated initial models, Mr. N saw a strong difference of opinion in one class, and decided to engage all of his students in a model competition. In preparation, he drew two models that represented the major ideas he saw being represented. The next day, he presented these models to both classes in which the lesson sequence was being taught.

When the second class began, the two models were already drawn on the board.

T: We added some things (to our model) in other classes, so I thought I'd show them to you. Somebody explained this model to me a little better (pointing to Model 1) and I thought I'd just share it with you because it is kind of interesting.

(The teacher describes Model 1 and gestures to make it clear that it shows air going in a tube from the lungs to the heart.)

T: And Model 2 was something like this [points to Model 2], same basic picture, the air comes in here [points to the vertical line at the top of the diagram, which represents the trachea] and the difference is, instead of the air going in a little tube down to the heart, the air made that transfer into the blood vessel in the lungs somewhere. And so … the oxygen gets ... into the blood here in the lung, the blood then goes to the heart .... So if you had to choose between these two ... you like one where you got a little tube with air ... going into the heart [points to Model 1]? Or do we like one where the blood is going into the lung [points to Model 2] and the lung is dropping off the air, and the blood goes to the heart?

In Model 2, instead of a pipe, there is a red arrow going from the lungs to the heart. Another red arrow goes from the heart to the big toe. Then a blue arrow leads from the toe back to the lungs instead of back to the heart. These three arrows form a larger circulatory loop. A label pointing to the lungs says, "A filter allows air in not liquids." Thus, in this model, there is a separation between air and liquid at the edge of the lungs, rather than air in the heart as in Model 1.In Model 1, the lungs are connected to the heart by a little tube. A circulatory loop goes from the heart down to the big toe and back, with a red artery and a blue vein. Labels on the diagram show that there is air in the lungs and liquid in the artery-vein loop, and that the heart is the "mover."

 

 

 

 

 

 

 

 

 

               Model 1                               Model 2

This initiated a series of animated discussions, alternating between small groups and whole class, where students evaluated both models. Eventually the class decided that both models were partly right and partly wrong. The teacher erased the parts of the models that were in contention. This resulted in a single partial model that the class agreed on, and the discussion shifted into an Improving the Model mode.

 
Teachers who describe this mode to students refer to it as a "model comparison" discussion rather than as a "model competition" discussion to avoid fostering an overly competitive attitude. They try to foster the attitude that the group is seeking to find the best ideas together. Teachers may also suggest that the discussion may produce an even better model that goes beyond either of the two being compared.
 

Example 2

The same cartoon model of a head as in the previous image, but annotated differently. This one has separate tubes from the nose and the mouth extending down through the neck and not joining together.Cartoon model of head, annotated with a single tube from nose and mouth going down the neck. Particles show that food is in that tube.In this example, the teacher did not plan ahead of time for model competition. The emergence of distinctly different student models surprised both the teacher and the observer-researcher, and the teacher had to think quickly on her feet for how to deal with the multiple ideas.  

The teacher had asked her students to draw a diagram of the throat and show what happens to an apple when you swallow it. Some students had drawn a single tube going down from the throat to the stomach or lungs, while others had drawn two independent tubes, one for food from mouth to stomach and the other for air from nose to lungs. Instead of immediately selecting a one- or two-tube model as best, the teacher led the students in evaluating and eventually discarding the two-tube model (“Can you breathe and swallow at the same time?”) and then evaluating and modifying a one-tube model (“What is there to keep the food from going into your lungs?”).

Here is the video of the Structure of the Throat discussion. See Examples 2 and 8 under Level II Strategies to Support Model Evaluation for two of the strategies that this teacher used, together with how the students responded to those strategies.

Example 3

This image is the same as Figure 2 in the Educator’s Tour. Black wavy lines extend along the top and bottom of the image, representing villi-lined intestinal walls. (Each wave represents a villus.) Green dots between the lines represent nutrients in the intestines. Students have added hand-drawn lines in red to represent their models of how the capillaries would be arranged in the villi. Model A has three vertical lines inside the intestinal wall, near a villus. Model B has a wavy red line following the surface of villi, inside the intestine next to the nutrients. Model C has branching tree-like structures inside each villus.Teacher and students were discussing where to locate capillaries with respect to the villi in the small intestine to increase nutrient absorption. The students came up with three ideas, and added them in red to a diagram being projected in front of the class.

Although none of the student additions (A, B, or C) were scientifically correct, they resulted in three initial models that could then be used in a Model Competition discussion, where each one was evaluated by the students for its strengths and weaknesses.

(For more about this lesson, see Providing a Partial Model under Level II: Supporting Model Generation.)

 

Supporting and Contributing Strategies

Model Competition contains repeated phases of:

III.  Evaluating a Model

which can be supported by:

II. Creative Reasoning Processes to Support Model Evaluation

There are many Visualization strategies that may be helpful. Among them:

I. Depictive Gestures
I. Scientific Drawings
I. Mental Simulations

 

Background

Some of the background for this category of discussion, and how it fits into the larger framework, is in the Level IV section of the Educator's Tour.

For more discussion on the theoretical underpinnings of this part of the framework, see the Introduction to the Full Theory page.

 

Articles, Papers and Websites

More in-depth discussion is found in the following paper by our team:

Large scale scientific modeling practices (Nunez-Oviedo & Clement, 2019)

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