Teacher Feature
Worth Their Weight
Overview
After visiting the War of 1812 Era in the Time Machine, students will learn about grams using coins as manipulatives.
Activity
After reviewing the information about the Large Cent from Time Machine's War of 1812 Era, display an overhead image of the 1811 Large Cent and show (image or actual) current circulating coins (quarter, dime, nickel and a cent (penny)). Review ideas learned from Time Machine's War of 1812 Era. Discuss metal content with students, explaining that in the 1800's the amount of metal a coin had matched its denomination, or how much it was actually worth. Write the following question on the board: How do weights of circulating coins today compare with a coin used in 1811? Distribute one "A Weigh We Go!" data sheet to each student. Ask the students to predict which coin they think weighs the most and the one that weighs the least. Have them record their predictions at the top of their data sheet.
Separate the class into groups of 23. Each group should have a balance scale and a bag of circulating coins. Display the overhead transparency of the 1811 Large Cent. Tell the students that in the year 1811, the cent coin in circulation was the Large Cent. It was minted from 17931857. Write the following information on the overhead and explain to the students that the characteristics of the coin are: it was made of 100% copper, weight was 10.89 grams and the diameter was 2829 millimeters. Circle the weight of the 1811 Large Cent, and have the students' record the information in all sections of the column labeled, Weight of Large Cent (in grams), so comparisons can easily be made for each coin.
Using the balance scale, have students weigh each of the coins to the nearest gram. Direct the students to record their answers on the data sheet. Discuss the students' predictions and findings. The students should have determined that the Large Cent is larger and heavier than all of the other coins listed in the data sheet. Using the weight of each of the coins from their data sheet, have the class find out how much more the Large Cent actually weighs. Write the following question on the board: How has the relationship between the amount of value a coin has and how much it weighs changed from the year 1811 to today? Discuss the concept of metal content in coins with the students, explaining that coins today do not have the equivalent value or amount of metal relating to their denomination. Talk with students about the metal content of today's coins, explaining that our one cent piece today (penny) is 99.2% zinc and .8% copper. Other coins such as the quarter, nickel and dime are 75% copper and 25% nickel. Have students write a reflection based on their findings for assessment.
Extension
Read the students a book about circumference such as:
 Sir Cumference and the First Round Table: A Math Adventure by Cindy Neuschwander
 Math Talk: Mathematical Ideas in Poems for Two Voices by Theoni Pappas
 Spaghetti and Meatballs for All by Marilyn Burns
 Adventures of Penrose the Mathematical Cat by Theoni Pappas
Review how to find the diameter and circumference of a circle with the students. Separate the class into groups of 23. Each group should have a centimeter ruler and a bag of coins from the previous activity.
Have the students find the diameter and circumference for each coin and compare the findings to the Large Cent. For a visual comparison, have the students draw an image of the 1811 Large Cent and our current one cent (penny) and compare the sizes.
Standards
The project described above reflects some of the national standards of learning as defined by the National Council for the Social Studies (NCSS), the National Council for Teachers of English (NCTE), and the International Society for Technology in Education. These standards are listed below:
Mathematics Standards
Measurement: Students will weigh various circulating coins in grams, and record their findings on a data chart for comparisons. Students will compare weights of coins and use subtraction of decimals to find the difference.
Science as Inquiry: Students use their skills of observation to weigh the coins, and gather appropriate data.
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