6.AT.2 Group 2 · Challenge

Practice Set · Part 1

Understand Rates and Unit Rates

Pick up where we left off

Name: Date: Group:

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

  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. Because this unit rate is money for one item, it has its own name: it is the unit price.
  5. 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. 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. 2

    Warm restartA bag holds 4 red marbles and 6 blue marbles. Write the ratio of red marbles to blue marbles in simplest form.

    1. A2:3
    2. B3:2
    3. C4:10
    4. D10

    How do you know?

  3. 3

    Warm restartWhat does the ratio 3:1 mean in words?

    1. AFor every 3 of the first amount there is 1 of the second
    2. BThe first amount is 3 more than the second
    3. CThere are 4 things altogether
    4. DThe two amounts are equal

    How do you know?

  4. 4

    Warm restartA bowl holds 4 apples and 6 oranges. What is the ratio of apples to the TOTAL pieces of fruit?

    1. A4:10
    2. B4:6
    3. C10:4
    4. D6:10

    How do you know?

3.2 Small Group · Group 2 · Practice SetPart 1 of 4
6.AT.2 Group 2 · Challenge

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.

  1. 5

    Think it throughWhat is the unit rate for the small bag?

    1. A$0.75 per cup
    2. B$0.70 per cup
    3. C$1.33 per cup
    4. D$2.25 per cup

    Why is that the answer?

  2. 6

    Think it throughWhat is the unit rate for the large bag?

    1. A$0.70 per cup
    2. B$0.75 per cup
    3. C$1.43 per cup
    4. D$5.60 per cup

    How do you know? Give a second reason as well.

  3. 7

    Think it throughWhich size is the better deal, and why?

    1. AThe large bag, because $0.70 per cup is less than $0.75 per cup
    2. BThe small bag, because $2.25 is less than $5.60
    3. CThe small bag, because it has fewer cups
    4. DThey are the same deal

    Explain your thinking. What would have to change for a different choice to be right?

  4. 8

    Back to the modelHow does finding the unit rate help you compare the booths?

3.2 Small Group · Group 2 · Practice SetPart 2 of 4
6.AT.2 Group 2 · Challenge

Practice Set · Part 3

Understand Rates and Unit Rates

Words and reasoning

Word bank · Banco de palabras

Rates and Unit Rates (Tasas y tasas unitarias)Rate (Tasa)Unit Rate (Tasa unitaria)Per (Por)Ratio (Razón)Unit price (Precio unitario)Better Buy (Mejor compra)Divide (Dividir)

Use the words

Fill each blank with a word from the bank.

Explain the thinking

  1. 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.
  2. 10

    Say moreHow did you find the cost per game (the unit rate) for each booth, and what did you divide?

  3. 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
3.2 Small Group · Group 2 · Practice SetPart 3 of 4
6.AT.2 Group 2 · Challenge

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.

  1. 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?

    1. A6 for $1.50 — $0.25 each
    2. B10 for $2.80 — $0.28 each
    3. CThey cost the same per pencil
    4. DNot enough information

    Explain your choice.

  2. 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?

    1. A5:13
    2. B8:5
    3. C5:8
    4. D13:5

    How do you know?

  3. 14

    From Lesson 3.1With 15 mains and 10 sides, what is the ratio of mains to TOTAL dishes?

    1. A3 to 5
    2. B3 to 2
    3. C15 to 10
    4. D2 to 5

    How do you know?

Be honest — this tells your teacher what to do next

I can…Not yetGetting thereGot 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