A Program of The Actuarial Foundation. Aligned with Common Core State and NCTM Standards.
Program Home Pages
Additional Resources

What is an actuary? An actuary is an expert in statistics who works with businesses, governments, and organizations to help them plan for the future. Actuarial science is the discipline that applies math and statistical methods to assess risk.

Background photo: © Inga Nielsen/iStockphoto.

About This Lesson Plan



Plan, Save, Succeed!

Lesson 3: Interest and Bank Accounts

In this "Plan, Save, Succeed!" lesson, students will learn about the importance of saving and the differences between certificates of deposit, checking, and savings accounts. In addition to using fractions, decimals, and percentages to calculate interest, students will also learn the difference between simple and compound interest.


  • Students will understand the importance of saving and the differences (advantages and disadvantages) between certificates of deposit (CDs), checking, and savings accounts. (financial literacy)
  • Students will understand the difference between simple and compound interest. (financial literacy and math)
  • Students will use fractions, decimals, and percentages to calculate interest. (financial literacy and math)
TIME REQUIRED: 20 minutes plus additional time for worksheet




1. Ask students if there are ways for kids to make money other than work, allowance, or gifts. Explain that banks and other financial institutions pay interest on certain accounts as an incentive to get people to deposit their money with them. They then use this money to make loans to companies and individuals. Banks make money from the interest they charge on the loans.

2. Indicate that financial institutions offer a number of different types of accounts:

Checking accounts give individuals the easiest access to their funds via checks, but pay little or no interest. Indicate that most banks require students of middle school age to have a parent as a cosigner when opening a checking account. Individuals also have access to their funds via their debit cards.

Savings accounts provide some interest but require the individual to visit a bank branch, use a debit card at an ATM, or go online to have access to his or her funds.

Certificates of deposit (CDs) have the advantage of offering higher interest rates than savings accounts, but have tighter restrictions on access to funds. Individuals purchasing a CD must commit to holding it for a period of time, generally ranging from six months to five years or more. Selecting the term of a CD involves some risk. When a long-term CD is purchased and interest rates later go up, the purchaser only receives the interest rate stated at the time of purchase. If it turns out that interest rates go down, the purchaser will be happy to have locked in a favorable rate.

People make decisions about the kind of account to open partly based on the amount of interest they'll earn, but also on how easily they can have access to their funds.

3. Indicate that interest is sometimes calculated as simple interest but is more frequently calculated as compound interest. Provide an example of each, explaining each formula:

  • The simple interest formula is I = PRT, where I is the amount of interest earned, P is the amount deposited (principal), R is the rate of interest, and T is the number of years. So if you deposited $100 for two years with an interest rate of 3½%, you would earn $100 x .035 x 2 or $7. (If necessary, explain how 3½% is converted to .035 in the calculation.)
  • The compound interest rate formula is A = P(1 + r/n)nt, where A is the ending amount, P is the amount deposited (principal), r is the interest rate, n is the number of compounding periods per year, and t is the number of years. The amount of interest earned is the ending amount minus the principal invested (A - P). Give an example of annual compounding. If you deposit $100 for two years at 3½% interest, you would end up with 100 x (1 + .035)2 or $107.12,