This Math Monday, you’ll get a sneak peak of the new Desmos activity Growth of Savings vs Investments, which is part of our upcoming Intro to Investing & Exponential Equations. Stay tuned for that release later this week!

This activity introduces students to exponential growth before they’ve learned anything about exponential functions by comparing the growth of $5000 in a savings account with 1% interest and the growth of $1000 in an investment account that earns a 7% annual return on average. 

The Set Up

First, students answer the core question: would you rather have $1000 to invest right now or $5000 to save? 

Then, students start to calculate how their money would grow in each account. They won’t need to know how to work with exponential functions: all they need to do is calculate a 1% or 7% increase from the previous amount. They even input an expression like 5000*1.01. 

Students can check their own answers, but you’ll get an alert as their teacher if they attempt the same problem more than 3 times. 

To avoid tedious calculations, students can then use a button to automatically fill in the rest of the table. 

Make a Prediction Using the Graph

Next, students see the same data presented on a graph. They write their observations, sketch how each account will grow, and predict which account will be worth more after 30 years. They can even read their classmates’ predictions!

Here’s where Desmos gets really cool - students can see the graph of the real account growth overlaid with their sketched prediction. 

Finally, students summarize what they’ve learned about exponential growth and investments and consider when it is better to save or invest. 

Where to Find NGPF’s Desmos Activities

You may be wondering where exactly you can find these great Desmos activities. If you’re using our Financial Algebra curriculum, you’ll find Desmos activities built directly into the Lesson Guides and Application Answer Keys. 

To look through NGPF’s library of Desmos activities, you can check out our Financial Algebra Collection.

Want More?

• Be the first to explore the new unit at our VPD: Financial Algebra: Investing and Exponential Functions; this Thursday at 2 pm Pacific
• Financial Algebra course page

Want another great investing question? Check out Question of the Day: Would you rather have $1,000,000 or start with a penny and double your money every day for 30 days?

About the Author

Kathryn Dawson

Kathryn (she/her) is excited to join the NGPF team after 9 years of experience in education as a mentor, tutor, and special education teacher. She is a graduate of Cornell University with a degree in policy analysis and management and has a master's degree in education from Brooklyn College. Kathryn is looking forward to bringing her passion for accessibility and educational justice into curriculum design at NGPF. During her free time, Kathryn loves embarking on cooking projects, walking around her Seattle neighborhood with her dog, or lounging in a hammock with a book.

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