Pedagogy in Action > Library > Interactive Lectures > Examples > How Much Work is Required: Intuition vs. Mathematical Calculation

How Much Work is Required: Intuition vs. Mathematical Calculation

This page and activity authored by James Rutledge, St. Petersburg College.
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This material was originally developed through Merlot
as part of its collaboration with the SERC Pedagogic Service.

Summary

This classroom activity presents Calculus II students with some Flash tutorials involving work and pumping liquids along with a simple question concerning the amount of work involved in pumping water out of two full containers having the same shape and size but different spatial orientations.

Students are given opportunities to address this question by means of a ConcepTest, a Question of the Day and a write-pair-share activity. The results are quite revealing and show that while students may have learned how to perform the necessary calculations, their conceptual understanding concerning work may remain faulty.

Learning Goals

To enable students to:

Context for Use

This activity can be carried out in either a small Calculus II class or a large lecture setting anytime during or after the application of integration commonly entitled Work has been covered.

The activity is comprised of five segments: Flash tutorials, ConcepTest, Question of the Day, write-pair-share activity and conclusion. The time required for the entire activity is approximately 45-50 minutes but fewer segments can be offered as a shorter alternative (see activity description below for individual segment times).

Description and Teaching Materials

Activity description:

Teaching Notes and Tips

In the ConcepTest, many students will respond that the work required is the same for both cones. This reveals the common misconception that emptying the containers requires the same amount of work since the containers have the same volume; quantity of liquid and distance traveled are often not taken into consideration until specifically pointed out and focused upon.

Another common error comes to light in the write-pair-share activity when the students perform the calculations necessary to find the amounts of work required. Some who had the correct intuitive understanding may be baffled by the seeming fact that their calculations don't agree with their intuition. What they don't realize is that they have made a very common error in assuming that the ratios involving the radius and height in each cone are the same when in actuality they are different.

This is a good opportunity to allow students to wrestle with the contradiction between their intuition and the results of their calculations and to enter into a discussion about this issue in more general terms and about how to resolve such contradictions. Bringing these misconceptions to light and correcting them are both eye-opening and rewarding for students.

Assessment

I generally give the students a grade for participation in this activity and sometimes grade their final calculations concerning the work required.

References and Resources

MERLOT description of the "Visual Calculus: Applications of Integration-Work" resource that is used in this activity.

Direct link to Visual Calculus which includes tutorials and animations (Flash and Java) that are helpful for students who are visual learners.

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