Journal Five

To begin the study of applications of exponential functions and lay a base of understanding for the growth formulas I ask the students to tell me a story. Instead of the teacher or the author of the textbook generating problems to be solved, I want the students to conceive of original problems. The topic is money...money which will be invested. I review the concepts of principal, interest and time with the students and demonstrate how to use a spreadsheet with values, formulas, and fill down options. The demonstration follows the guidelines set up in Larry Shook's and Mike Callinan's EMT668 unit on the algebra of financal planning. To see the unit click here. Students quickly appreciate the graphing capabilities of ClarisWorks and the power of using the spreadsheet to see what actually happens in each compounding period.

I request a laboratory report from the students as a method of evaluating the activity. In the May 1996 issue of Mathematics Teacher are the instructions students follow for the reports. I quote directly from Jennifer Mayer and Susan Hillman's article, "Assessing Students' Thinking through Writing".

Introduction

Restate the problem in your own words.
Explain how you began to try to solve the problem.
How did you decide on a strategy?

Body

What strategy or strategies did you use to solve the problem?
Did you try something that was unsuccessful? Explain.
Be sure to show all graphs, charts and models.
Tell about the tools used, such as calculators, manipulatives, or rulers.
Use precise mathematical language.

Conclusion

What conclusions can you draw from this problem?
How can you justify your conclusions?
Extend the problem by-
connecting this problem to a problem studied earlier or generalizing a rule