Lesson 10What Are Percentages?
Learning Goal
Let’s learn about percentages.
Learning Targets
I can create a double number line with percentages on one line and dollar amounts on the other line.
I can explain the meaning of percentages using dollars and cents as an example.
Lesson Terms
- percent
- percentage
Warm Up: Dollars and Cents
Problem 1
Find each answer mentally.
A sticker costs 25 cents. How many dollars is that?
A pen costs 1.50 dollars. How many cents is that?
How many cents are in one dollar?
How many dollars are in one cent?
Activity 1: Coins
Problem 1
Complete the table to show the values of these U.S. coins.
The value of a quarter is 25% of the value of a dollar because there are 25 cents for every 100 cents.
coin | penny | nickel | dime | quarter | half dollar | dollar |
---|---|---|---|---|---|---|
value (cents) |
Problem 2
Write the name of the coin that matches each expression.
25% of a dollar
5% of a dollar
1% of a dollar
100% of a dollar
10% of a dollar
50% of a dollar
Problem 3
The value of 6 dimes is what percent of the value of a dollar?
Problem 4
The value of 6 quarters is what percent of the value of a dollar?
Are you ready for more?
Problem 1
Find two different sets of coins that each make 120% of a dollar, where no type of coin is in both sets.
Activity 2: Coins on a Number Line
Problem 1
A $1 coin is worth 100% of the value of a dollar. Here is a double number line that shows this.
The coins in Jada’s pocket are worth 75% of a dollar. How much are they worth (in dollars)?
The coins in Diego’s pocket are worth 150% of a dollar. How much are they worth (in dollars)?
Elena has 3 quarters and 5 dimes. What percentage of a dollar does she have?
Lesson Summary
A percentage is a rate per 100.
We can find percentages of $10 using a double number line where 10 and 100% are aligned, as shown here:
Looking at the double number line, we can see that $5.00 is 50% of $10.00 and that $12.50 is 125% of $10.00.