Students will use the % key to collect data about percentages of a given number. They will organize the data and look for patterns in percents. (For example, 10% of 20 is twice as much as 5% of 20.)

After students use manipulatives to develop the meaning of percent (1% = 1 part out of 100 parts), have them explore what happens when they press % on the calculator.

Present the following scenario to students:

Metropolis East (M.E.) and Metropolis West (M.W.) are neighboring cities. The sales tax in M.E. is 10%, but the sales tax in M.W. is only 5%. Collect data and display your results for each percent in a table to compare the amounts of money you would pay for tax on various items in each city.