The Life and Times of Percy Julian

For Teachers

Activity 7A.2 (Lab Activity)
Separating Coins

Note to Teachers: The student version of this activity is a thought experiment that prepares students for a teacher demonstration of the coin separator as described below. Have students perform the thought experiment before the actual demonstration.

Lesson Overview In this exercise, you will introduce the idea of separation of macroscopic mixtures by demonstrating how a coin sorter separates a mixture of loose change into pennies, nickels, dimes, and quarters. The students must then try to figure out how the coin sorter accomplishes the separation.
Learning Objectives Students will speculate as to how the coins are separated. They may guess that the coins are sorted by mass or size. (Both may be used, depending on the make and model of coin sorter you’re using.) Either way, the students by themselves will arrive at the conclusion that separations take place because of differences in size or mass or both.
Lesson Concepts
  1. Students learn to use models (through a coin sorter) to understand the basic principles of separation of a mixture of materials.
  2. Mixtures contain more than one kind of material.
Materials Required
  • 3-oz. paper cup
  • Enough loose change to fill the cup
  • Automatic coin sorter
Skills Required

Middle school students need to be able to follow instructions and to work cooperatively.

Time Required

10–15 minutes, including introduction.


Warn students not to swallow or throw coins.

Student Ability Level and Grouping

This activity may be done as a teacher demonstration. (It could also be adapted to be done by middle school students working in pairs.)

Procedural Notes
  1. Have the students record their ideas on the Investigation Record Sheet for this activity.
  2. Particularly bright students may think of magnetic properties as the basis for separation. While magnetic properties aren’t generally used by coin sorters, vending machines use magnetic properties to discern real coins from slugs.
  3. Speaking of vending machines, if you are unable to get a coin sorter, you might ask students to figure out how a vending machine knows what kind of coin is fed into it.
Assessment See Activity 7A.7, Assessment: A Challenging Separation.

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