ACTIVITY 2.4: The Mealworm and Mr. Short Puzzles

To help you understand the difference between concrete and formal reasoning patterns, two puzzles are described below, followed by secondary students answers and their explanations of their answers.

Materials

Paperclips, copies of the puzzles

Procedure

1. First perform the puzzles yourself, writing your answers and explanations as the students did on separate sheets of paper.

2. If you are able to have secondary students complete the puzzles, you can use their responses to respond to the following questions, as well as the students responses included here.

Minds On Strategies

When you have finished completing the puzzles, answer these questions.

1. What differences in reasoning did you find among the students' responses to
a. The mealworm puzzle

b. The ratio puzzle

2. What similarities did you observe in the thinking patterns of Norma, David and Dolores?

3. What similarities did you observe in the thinking patterns of Jean, John and Harold?

4. Which students are using concrete reasoning patterns? Which are using formal reasoning patterns?

5. What are some characteristics of

a. Concrete reasoning?

b. Formal reasoning?

 Figure 2.27 The Mealworm and Mr. Short Puzzle

The Mealworm Puzzle

An experimenter wanted to test the response of mealworms to light and moisture. To do this he set up four boxes as shown in Figure 2.28. He used lamps for light sources and constantly watered pieces of paper in the boxes for moisture. In the center of each box he placed 110 mealworms. One day he returned to count the number of mealworms that had crawled to the different ends of the boxes.

The diagrams show that mealworms respond to (response means move toward or away):

A. light but not moisture.

B. moisture but not light.

D. both light and moisture

D. neither light nor moisture

Please explain your choice.

The Mr. Short Puzzle

The drawing in Figure 2.29 is called Mr. Short. We used large round buttons laid side-by-side to measure Mr. Short's height, starting from the floor between his feet and going to the top of his head. His height was four buttons. Then we took a similar figure called Mr. Tall, and measured it in the same way with the same buttons. Mr. Tall was six buttons high.

Now please do these things:

1. Measure the height of Mr. Short using paper clips in a chain. The height is_______.

2. Predict the height of Mr. Tall if he were measured with the same paper clips.________

3. Explain how you figured out your prediction. (You may use diagrams, words, or calculations. Please explain your steps carefully.)

Responses to the Mealworm and Mr. Short Puzzle

Students

Mealworm Puzzle Responses

Mr. Short Puzzle Responses

Student 1 (Norma, Age 12)

D. "Because even though the light was moved in different places the mealworms didn't do the same things.

Prediction for Mr. Tall: 8-1/2 paper clips.

Explanation: "Mr. Tall is 8-1/2 paper clips tall because when using buttons as a unit of measure he is 2 units taller. When Mr. Short is measured with paper clips as a unit of measurement he is 6-1/2 paper clips. Therefore, Mr. Tall is 2 units taller in comparison which totals 8-1/2."

Student 2. (Jean, Age 13)

B. "I, II, and III show that mealworms seem to like the light, but in III they seem to be equally spaced. This leads one to believe that mealworms like the dryness and the reason in pictures III and IV they are by the light is because of the heat that the light produces which gives a dryness effect.

Prediction for Mr. Tall: 9.2 paperclips.

Explanation: "The ratio using buttons of height of Mr. Short and Mr. Tall is 2 : 3. Figuring out algebraically and solving for x:

6-1/2

2/3 = x gives you 9.2 as

the height in paper clips."

Student 3 (David, Age 14)

A. "They usually went to the end of the box with the light."

Prediction for Mr. Tall: 9 paperclips tall.

Explanation: "I figured out by figuring that Mr. Small is 2/3 as tall as Mr. Tall."

Student 4. (John, Age 16)

C. Boxes I and II show they prefer dry and light to wet and dark. Box IV eliminates dryness as a factor, so they do respond to light only. Box III shows that wetness cancels the effect of the light, so it seems they prefer dry. (It would be clearer if one of the boxes was wet-dry with no light."

Prediction for Mr. Tall: 9 clips (pencil marks along Mr. Short).

Explanation: "I estimated the middle and then on-fourth of Mr. Short. That's about the size of one button. I measured the button with my clips and found 1-1/2. So then I counted out six times 1-1/2 buttons and got nine."

Student 5. (Dolores, Age 17)

C. "In the experiment 3 mealworms split 1/2 wet, 1/2 dry. So it's safe to assume that light was not the only factor involved.

Prediction for Mr. Tall: 8 paper clips tall.

Explanation: "If Mr. Short measures 4 buttons or 6 paper clips (2 pieces more than buttons), then Mr. Tall should be 2 paper clips more than buttons.

Student 6. (Harold, Age 18)

A. "Because there are 17 worms by the light and there are only 3 by the moisture.

Prediction for Mr. Tall: 9-3/6

Explanation: "Figured it out by seeing that Mr. Tall is half again as tall as Mr. Short, so I took half of Mr. Short's height in clips and added it on to his present height in clips and came up with my prediction."

Concrete versus Formal Thinking: Implications

While reading through the responses to the two puzzles, you should have noticed that some of the answers were more complete, more consistent, and more systematic that others. Each answer represents the reasoning of the student who wrote it. Yet surprising as it may seem, inconsistent and incomplete answers were just as common as complete and consistent ones. The patterns of thinking that the students show as responses to these puzzle problems are integral aspects of Piaget's theory of cognitive development.

In the mealworm puzzle students using concrete reasoning tend to focus on one variable and exclude the others. The student cannot detect the logic of the experiment that allows one variable to be isolated and separated so that they can be dealt with as distinct causal agents. Formal reasoning patterns are shown when students realize that variables are held constant while only one is allowed to change, as in boxes II or IV, or comparing I with III. The formal thinker considers all possible causal factors to test the hypothesis that light or moisture is responsible for the distribution of mealworms.

In the Mr. Short puzzle, concrete reasoning is recognized by students who simply add the extra amount to the height of Mr. Tall. This type of thinking is a much more direct measure of qualitative difference than is the ratio, which the student makes only by making a correspondence between each individual button and paper clip. Formal thinkers understand that each button corresponds to a certain number of paper clips. Once the ratio is known, the answer is found by calculation.

Concrete thinkers need reference to familiar actions, objects and observable properties. They use reasoning patterns that include conservation, class inclusion, reversibility and serial ordering. Their thinking shows inconsistencies among various statements they make, and often contradict themselves. Most of the students you will teach are concrete thinkers, even though Piaget has suggested that the formal stage of development begins at about age 14. Studies have shown that many adolescents and adults do not develop formal thinking capacities.

Formal or abstract thinkers reasons with concepts (F=ma), indirect relationships, properties and theories. They are able to use a wide range of thinking patterns, including combinatorial reasoning, proportional reasoning, control of variables, and probabilistic reasoning. Formal thinkers are able to plan out a course of action, manipulate ideas in their minds, and actively check the validity of their own ideas.