Investing · Strategy · Worksheet Lesson
Investment Options: Where to Invest Your Money
A lesson and worksheet on how to compare investment options — using the simple interest formula and a small dose of algebra to figure out how much money to allocate to each choice when you have multiple options at different rates. Lesson is free; printable worksheet requires Full Membership.
What Students Learn
Learning objectives
- How to use the simple interest formula I = prt to calculate the interest earned on an investment
- How to compare different investment options — savings accounts, certificates of deposit (CDs), stocks, loans — on the same math
- How to use basic algebra — letting X represent an unknown amount of money — to split funds across two investment options
- How to build an I = prt table that organizes principal, rate, time, and total interest across competing investment choices
- How to determine the principal invested in each of two options when you know the total principal, both rates, the time period, and the target total interest
- How investment math connects to real-world financial decisions about where to put savings
I = p × r × tWhere I = interest earned, p = principal (amount invested), r = annual interest rate as a decimal, and t = time in years.
For Teachers
How to use this lesson
This lesson is built around a real-world finance problem: given $10,000 to split between two investment options at different rates, how much should go to each to hit a target total interest? Students need to use the simple interest formula I = prt and basic algebra together — setting up an I = prt table with X for the unknown principal in one option and the rest of the total in the other.
Suggested procedure: Start with a warm-up reviewing decimal-to-percent conversions (students will need this for the rate). Motivate the lesson by asking what investment options students or their parents have used — savings accounts, CDs, stocks, bonds. Demonstrate the I = prt formula on a single investment (e.g., $10,000 at 5% for 1 year earns $500). Then introduce the two-investment version. Have students complete the printable worksheet as classwork or homework.
Aligns with NCTM Standards 1, 2, 6, 7, 8, 9, and 10. Strong cross-curricular bridge between consumer math and personal finance — the same algebra skills used here apply to many real-world allocation problems.
Printable Worksheet · Full Membership
Investment Options — Practice Worksheet
Practice problems applying the I = prt formula and algebra to split an investment across two options — with an answer key for teacher use.
The lesson content above is free to use. The printable worksheet is available with Full Membership.
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