# Lesson Plan

## Can You Find the Difference?

Main Subject Area: Science

Duration of Lesson:  45 minutes

Keywords:

• Density
• Fulcrum
• Simple Machines
• Weight

Brief Description:

Students will create their own balance to determine a difference in the weight (and composition) of cents made in different years.

National Standard(s):

• Science as inquiry
• Physical science

Objectives:

Students will create a balance to compare the weight of cents (pennies).

Student will divide the cents into categories based on weight.

Students will make observations about the cents in each category.

Students will hypothesis why there are differences in the cents.

Materials (online):

http://www.frbatlanta.org/invoke.cfm?objectid=83FD41FF-9AF0-11D5-898400508BB89A83&method=display_body

Materials (offline):

At least 10 cents (pennies) per group, minted between 1980 and today. Make sure you have some 1982 and 1982D.

Rulers

Index card

Lab journals

Coins Used in Lesson:

Circulating U.S. cents, dated before 1982 and after 1982

Procedures (online):

Research changes in the composition of circulating U.S. cents using the links listed under Materials (online).

Procedures (offline):

1. Tell the students that they will be working in groups to discover a secret about cents. Separate students into groups of 4.

2. Provide each group with a bag of one cent coins. Explain that there is something different about the cents in the bag that the students need to find out.

3. Instruct each group to create a balance using an index card and a ruler. They will fold the index card in half to act as the fulcrum for the ruler. Tell the students to first balance the ruler on the index card to find the balance point of the ruler.

4. Next, direct the students to take one cent and place it on one end of the ruler. Then they should take each of the remaining cents and compare their weight to the initial cent (constant). The groups need to make sure they always keep the ruler at the same balance point and always use the same cent for comparison. They should place all coins that are heavier than the constant in one pile. They should place all coins that are the same weight as the constant in a second pile, and all that are lighter than the constant in a third pile.

5. After comparing all the cents, students should end up with two groups, one containing cents minted from 1980 – 1982 and a second group dated 1982 – today.

6. Students should conclude that something happened in 1982. Student can research on the Internet to find out what happened in 1982. They can also include their hypothesis as to why the United States Mint changed the composition of the one cent coins to include zinc in 1982.

7. Students should describe their procedures in their lab notebook. They can include what happened in 1982 if they were able to find out the information online. Student can include their own hypotheses as to why the weight is different in the coins.

Assessment / Evaluation:

Students can be assessed on their written description of their procedures including their ideas on why the composition of the cent has changed.

Differentiated Learning Options:

Students can compare the weight of other coins and see if there is a difference in weight for them also.