Simple Interest & Loan Cost: Borrow or Wait?
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The lab
⭐ BORROW OR WAIT? — A REAL-WORLD MONEY LAB ⭐
What students do
- The $600 Laptop — step into a real borrowing scenario with a clear “I can” target
- Decode Your Loan Quote — read an authentic loan quote (principal, rate, term, monthly payment)
- Build the Interest by Hand — apply I = P × r × t, including a time-unit watch-out
- Your Simple Interest Loan Calculator — four “what-if” tasks in a self-calculating spreadsheet
- Two Loan Offers, Make the Call — compare total cost, not the monthly payment, and justify the better deal
- Show What You Know — a scored mastery check on a fresh loan
- Reality Check — reflection + a real-world connection
Real math, done right
The interest work (7.RP.A.3) is done BY the student — twice, by hand, and it's assessed. Every interest and total-repayment figure is exact and verified to the cent, with a labeled note that real loan rates vary widely (about 7–36%) and many loans compound rather than staying simple — a natural bridge to the companion Compound Interest lab.
Print or digital
Print-and-go, or assign the editable Word packet in Google Docs and the calculator in Google Sheets. No devices today? A Printed Calculator Readouts page lets a fully print-only class run the whole lab.
What is included
- 10-page student lab (PDF + editable Word)
- Self-calculating spreadsheet (Excel / Google Sheets)
- 2-page teacher guide with full answer key + 10-point rubric
- Printed Calculator Readouts (print fallback) + Terms of Use
More Money Labs
Standard codes refer to the Common Core State Standards for Mathematics. Math Class 678 is an independent publisher, not affiliated with, sponsored by, or endorsed by NGA Center or CCSSO. Every product is sold on Teachers Pay Teachers.