Lesson 1: Rates and Unit Rates6.AT.2

I can…

I can find a unit rate to compare prices and decide the better buy.

Key words

• Rate — A ratio comparing two amounts with different units, like miles per hour.
• Unit Rate — A rate for just 1 of something, like cost for 1 item.
• Per — For each one. Example: 5 dollars per book.
• Ratio — A way to compare two amounts, like 3 to 2.
• Better Buy — The choice that costs less for each item.
• Divide — Splitting a total into equal groups.

Steps

1. Booth A charges $3 for 5 games. I want the cost for just 1 game.
2. I divide the cost by the games: $3 ÷ 5 = $0.60.
3. So Booth A costs $0.60 per game. That is the unit rate.
4. Now I can compare this booth fairly with any other booth.

Try it

A store sells 6 pencils for $1.50 and 10 pencils for $2.80. Which is the better buy?

Check your answer

6 for $1.50 — $0.25 each

$1.50 ÷ 6 = $0.25 per pencil. $2.80 ÷ 10 = $0.28 per pencil. $0.25 < $0.28, so 6 for $1.50 is the better buy.

Sentence starter

I know ___ because ___.

Goal: I can explain my choice using the words rate, unit rate, per, and better buy.