Practice Set · Part 1
Understand Rates and Unit Rates
Pick up where we left off
Where we left off
Our goal: I can find a unit rate to compare prices and decide the better buy, explain how I can tell, and judge a case I have not seen before.
The big idea: To find a unit rate, divide the total cost by the number of items. A unit rate that gives a cost is called a unit price, and the lower unit price is the better buy — and you can say why it is true, and where it would stop being true.
Model to copy — Watch me
- Booth A charges $3 for 5 games. I want the cost for just 1 game.
- I divide the cost by the games: $3 ÷ 5 = $0.60.
- So Booth A costs $0.60 per game. That is the unit rate.
- Because this unit rate is money for one item, it has its own name: it is the unit price.
- Now I can compare this booth's unit price fairly with any other booth's.
Start here
You did these with your group. Now do them on your own — the model above is yours to copy.
- 1
Same stepsFinish what the group started. Use the model above, step for step.
Try it together — then prove it: A booth charges $4 for 8 games. What do we divide? We divide cost by games: $4 ÷ 8 = ? What is the unit price, the cost for just 1 game? ($0.50 per game.) Now prove it: say why that move had to work at all — not just that it did.Show your work - 2
Warm restartA bag holds 4 red marbles and 6 blue marbles. Write the ratio of red marbles to blue marbles in simplest form.
- A2:3
- B3:2
- C4:10
- D10
How do you know?
- 3
Warm restartWhat does the ratio 3:1 mean in words?
- AFor every 3 of the first amount there is 1 of the second
- BThe first amount is 3 more than the second
- CThere are 4 things altogether
- DThe two amounts are equal
How do you know?
- 4
Warm restartA bowl holds 4 apples and 6 oranges. What is the ratio of apples to the TOTAL pieces of fruit?
- A4:10
- B4:6
- C10:4
- D6:10
How do you know?
Practice Set · Part 2
Understand Rates and Unit Rates
Keep going
You answered these out loud. Now write them.
Answer, then say how you know — the reason is the part that counts.
- 5
Think it throughWhat is the unit rate for the small bag?
- A$0.75 per cup
- B$0.70 per cup
- C$1.33 per cup
- D$2.25 per cup
Why is that the answer?
- 6
Think it throughWhat is the unit rate for the large bag?
- A$0.70 per cup
- B$0.75 per cup
- C$1.43 per cup
- D$5.60 per cup
How do you know? Give a second reason as well.
- 7
Think it throughWhich size is the better deal, and why?
- AThe large bag, because $0.70 per cup is less than $0.75 per cup
- BThe small bag, because $2.25 is less than $5.60
- CThe small bag, because it has fewer cups
- DThey are the same deal
Explain your thinking. What would have to change for a different choice to be right?
- 8
Back to the modelHow does finding the unit rate help you compare the booths?
Practice Set · Part 3
Understand Rates and Unit Rates
Words and reasoning
Word bank · Banco de palabras
Use the words
Fill each blank with a word from the bank.
- A rate compares different units; a ___ ___ compares a quantity to exactly 1 unit.
- A ratio that compares two quantities with different units is a ___.
- A rate that tells the cost or amount for one unit is a ___.
- The word that means 'for each one' is ___.
Explain the thinking
- 9
Find the mistakeAnother student made this exact mistake in this lesson. Explain why it is wrong, then write what they should have done.
The mistake: A common mistake in Rates and Unit Rates is comparing total costs instead of unit rates: a student sees Pack X at $4. - 10
Say moreHow did you find the cost per game (the unit rate) for each booth, and what did you divide?
- 11
Write your ownWrite your own problem about this situation, then solve it and show the answer. The situation: Two arcade booths sell game tokens. One booth advertises 5 tokens for $3.00, and the booth next to it advertises 8 tokens for $5.00. The signs are big and colorful, and each lists a different number of tokens for a different price.
Show your work
Practice Set · Part 4
Understand Rates and Unit Rates
Show what you know
Last check
These two come from Lesson 3.1. If they are shaky, that is the lesson to revisit — not this one.
- 12
Show what you knowExplain your thinking — A store sells 6 pencils for $1.50 and 10 pencils for $2.80. Which is the better buy?
- A6 for $1.50 — $0.25 each
- B10 for $2.80 — $0.28 each
- CThey cost the same per pencil
- DNot enough information
Explain your choice.
- 13
From Lesson 3.1Explain your thinking — A bag of trail mix contains 8 peanuts and 5 raisins. What is the ratio of raisins to total pieces?
- A5:13
- B8:5
- C5:8
- D13:5
How do you know?
- 14
From Lesson 3.1With 15 mains and 10 sides, what is the ratio of mains to TOTAL dishes?
- A3 to 5
- B3 to 2
- C15 to 10
- D2 to 5
How do you know?
Be honest — this tells your teacher what to do next
| I can… | Not yet | Getting there | Got it |
|---|---|---|---|
| I can find a unit rate to compare prices and decide the better buy, explain how I can tell, and judge a case I have not seen before. | |||
| I can explain why it works: To find a unit rate, divide the total cost by the number of items… | |||
| I can justify my answer to a skeptic and connect it to a second strategy or representation. |
One question I want to ask my group next time