This activity is intended to supplement Algebra I, Chapter 3, Lesson 7.
Time Required: 15 minutes
Topic: Linear Equations
Estimation and mental math
Teacher Preparation and Notes
This activity serves as a good introduction to using formulas that involve percentages.
The student worksheet provides instructions and questions to guide inquiry and focus observations.
Problem 1 – Percentage %
Problem 2 – Using an Equation
The student activity gives some hypothetical prices for various items that may be of interest to them. Students will select three of these items.
Second, students are to sum up the three individual prices and multiply this sum by the tax rate they chose to use in this example.
Students should see that these two amounts are almost the same, varying only by a penny.
Note that the amounts are almost the same because of the distribution property.
Note: Make sure the students have converted the tax rate to a non-percentage before finding the taxes paid.
Are there different tax rates for the state in which you live for products and services?
Examine a receipt from a store (other than a grocery store, since there is often no tax on food) and determine if the tax rate charged is correct.
Do an internet search of “sales tax by state” to find the real tax information from various states and use this information to compare the tax paid if the item was purchased in another state. (www.taxadmin.org/fta/rate/sales.html).
Problem 3 – Mental math and estimating