Rule Of 72 Worksheet

A rule of 72 worksheet is usually a single calculation: pick a rate of return, divide it into 72, and get an estimate of how many years an investment takes to double. This worksheet builds that calculation into a longer activity on investment risk, so students use the Rule of 72 for real before they move on to classifying assets and comparing investing strategies.

The first two questions are the core of it. Students are told that Michael invests $1,000 at a 6% average annual return and asked what it's worth after 36 years, then asked the same question at a 12% return. The jump between the two answers is the entire point: doubling twice as often over the same stretch of time doesn't just double the outcome, it multiplies it many times over. That's the Rule of 72 doing real work, not just being recited as a formula.

From there, the worksheet moves on to a different set of skills: classifying assets like cash, real estate, and corporate bonds by time horizon and risk level, comparing active versus passive investing, and identifying why the average investor underperforms the market. One question in the middle of all this, question 3, asks students to define needs versus wants — it's a single grounding question about household risk, not the focus of the sheet, and teachers who only want the Rule of 72 portion can stop after question 2.

Used in full, this works well as a review of a risk and diversification unit, with the Rule of 72 calculation up front doing the heavy lifting. Below is the worksheet exactly as it appears in the Rapunzl curriculum, followed by teacher notes on how to use it in class.

This activity is from Module 4 of the Rapunzl curriculum, The Power of Debt & Bonds.

Debt, Doubling & Managing Risk

The Rule of 72 is a simple way to determine how long an investment will take to double. Remember that by dividing 72 by the annual rate of return, we can estimate how many years it will take for an investment to double.

1. Using the information above, let’s assume that Michael invests $1,000 at a 6% average annual return. What is the value after 36 years?

A. $4,000 B. $6,000 C. $8,000 D. $13,000

1. Now let’s assume that Michael finds a different opportunity to invest $1,000 at an average annual return of 12%. What is the value of the investment after 36 years?

A. $13,000 B. $64,000 C. $128,000 D. $48,000

1. What are the differences between “wants” and “needs”? Provide examples of each.

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1. True or False: Past investment returns provide an accurate indication of future performance of an investment?

A. TRUE B. FALSE

1. Circle whether the identified item is a short-term investment, long-term investment, or not an investment.

1. For the identified items below, please circle whether the asset is low, medium or high risk.

1. True or False: Active investors trade a lot more with the hope of beating the market. Passive funds rely on gaining the returns of the broader market. Who is statistically more likely to be more successful?

A. ACTIVE INVESTORS B. PASSIVE INVESTORS

1. Circle the correct answer: Does diversifying investments increase or decrease risk compared to a single investment?

A. INCREASE B. DECREASE

1. The average investor’s return is far lower than the market average return because of which of the following? Circle all that apply.

A. People invest irrationally based on emotion. B. Investors try to time the market. C. Frequent trading results in more commissions. D. Investors chase returns and are scared to cut losses. E. All Answers Are Correct

1. True or False: Lower costs & expenses are an important thing to look for when evaluating an ETF, Mutual Fund, or Hedge Fund.

A. TRUE B. FALSE

1. True or False: Passively managed funds or ETFs that do not place a lot of trades, generally have higher costs & expenses than their actively managed counterparts?

A. TRUE B. FALSE

1. You should aim to save at least what percent of your income?

A. 78% B. 6% C. 3% D. 15%

Teacher Notes

Questions 1 and 2 are worth slowing down on, since they ask students to apply the Rule of 72 conceptually rather than by name. If your class covered the rule explicitly, point out that the jump from a 6% to a 12% return doesn't just double the outcome, it more than triples it over 36 years, because the doubling happens more often.

Question 3 is a quick detour into needs versus wants, worth a short discussion but not a full lesson on its own. Ask a few students to share their definitions out loud before moving on. You'll usually get a mix of "needs are things you can't live without" and more specific answers involving housing, food, and transportation. Either is a fine starting point, and it's fine to spend no more than a couple of minutes here before returning to risk and doubling time.

Questions 5 and 6 work well as a partner activity. Have students fill in both tables together and then compare notes with another pair before you review as a class. Disagreements on classifying art or foreign equities usually generate the best discussion.

Questions 9 through 12 shift the frame from what to invest in to how to behave as an investor. That shift is worth calling out explicitly, since students often treat these questions as unrelated to the earlier risk-classification work.

This worksheet is one piece of the full Power of Debt & Bonds unit inside the Rapunzl teacher portal, where activities like this one sit alongside articles, guided practice, and a classroom investing simulator built for grades 6–12.

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