8.12.B

Math8th Grade

The Standard

calculate the total cost of repaying a loan, including credit cards and easy access loans, under various rates of interest and over different periods using an online calculator

Texas Essential Knowledge and Skills for Mathematics

Teacher's field guide

What This Standard Means

What Students Need to Do

Students enter a loan amount, interest rate, and repayment period into an online calculator. They find total repayment and interest paid, then compare how different rates and terms affect cost.

What Mastery Looks Like

Students enter loan details correctly and identify the total repayment and total interest. They compare loan options and explain how a higher rate or longer repayment period affects cost.

Common Misconceptions

Students may confuse the monthly payment with the total amount repaid. They may treat APR as a one-time fee or assume a longer term costs less because its monthly payment is lower. Some expect minimum credit card payments to clear a balance quickly.

How to Assess It

Give students a $1,000 loan at 18% APR for 12 months and 24 months. Using an online calculator, they must record and compare total repayment and interest paid.

Lesson moves

Ways to Teach It

  1. Give pairs loan scenario cards to calculate online, then sort the cards from least to greatest total repayment.

  2. Ask students to write which matters more when comparing loans, monthly payment or total repayment, and support their answer with numbers.

  3. Play Loan Match, where students match principal, rate, and term cards to printed calculator results.

  4. Compare sample credit card, payday loan, and bank loan offers for the same purchase, including total repayment and interest.

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