"Penny Prediction" Lesson Plan

Topic: Geology (Math skills necessary also)

Grade: Middle School to High School

Objectives:
- to predict why pennies vary in weight.
- to test a hypothesis for its validity.
- to determine why pennies have different weights.
- to incorporate math skills into a problem-solving approach.


Procedure:
- Divide the class into groups of 2.
- Have each pair count out 50 pennies.
- Weigh pennies (all 50)
- Record (best to make a data chart)
- Compare weights as a class.
- (This data can be listed from highest to lowest and a bar graph can be created.)
- Have students "guess" why the same number of pennies has different weights. List and discuss these on the chalkboard.
(Possible reasons: miscounted, color (dull vs. shiny), age (worn away metal, types of metal used)

** Facts for Teacher: Pennies made before 1983 were made of
97% copper and 3% zinc. Beginning in 1983, however, pennies were made of 3% copper and 97% zinc due to the expense
of copper.

- To test the age factor, have groups make a stack of pre-1983 pennies and a stack of post-1983 pennies of the same number.
- Using scale, weigh each stack and compare. Record in data chart.
- Test the stacks also by displacement using graduated cylinders. Record data on chart.

** Should discover: Pre-1983 pennies weigh more since copper is denser than zinc.

- Use periodic table to verify weights of copper and zinc.
- Have groups graph all results and display. Discuss.

Source: Teaching and More