Education Technology

Activities

• Subject Area

• Math: Algebra I: Linear Functions

9-12

15 Minutes

• Device
• TI-Nspire™ Navigator™
• TI-Nspire™
• TI-Nspire™ CAS
• Software

TI-Nspire™
TI-Nspire™ CAS

2.0

Taxes & Tips

Activity Overview

In this activity, students will increase their understanding of the use of the formula T = r × p, which is encountered both in the real world and in the typical Algebra 1 class. They will calculate the amount of taxes and tips exactly, and then use estimation.

Key Steps

• In this activity, students will explore the taxes and tips percentages commonly used in stores and restaurants. They will first develop the pattern of converting a percent to a decimal.

• Then students will use the dynamic tax equation model to calculate the tax on several items given in a spreadsheet. They will compare the difference of calculating the taxes on individual items, then summing to the calculating the sum of the item prices multiplied by the tax rate.

• Students will finally use mental math estimation to calculate 15% or 20% of a restaurant bill or calculate the tax on a high priced item. They will compare their estimation to the actual answer.