Save or Play:

An Instructional Unit

Using MS Excel


by Mike Callinan

Cedar Shoals Unit. This unit, called "Save or Play", was a one-day unit given to a Cedar Shoals High School Pre-Algebra class. The objective was to teach them how to manipulate equations and a variable on a spreadsheet (Microsoft Excel, in this example) and also give them a valuable lesson for their future. The spreadsheet compares two saving patterns in columns B and C, each saving annually at 5 percent interest, the amount stored in cell D1. The years are represented in column A.

The first student (column B) decides to start saving immediately for ten years while the other student (column C) decides to "play". The second student finally decides to start saving after ten years while the first student decides to "play", letting his savings draw interest. The spreadsheet shows how long it takes for the second student to catch up with the first.

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