Practice Set · Part 1
Understand Ratios
Pick up where we left off
Where we left off
Our goal: I can write and describe a ratio that compares two quantities, explain what each part stands for, and build one for a situation I have not seen before.
The big idea: A ratio compares two quantities, and the order you write them in matters. You can write a ratio in words or with a colon, and you can draw it with a tape diagram or a double number line — and you can say why it is true, and where it would stop being true.
Model to copy — Watch me
- Chef Reyes uses 3 cups of apple juice for every 2 cups of sparkling water.
- I am comparing two amounts: apple juice and sparkling water.
- I write apple juice to sparkling water, in that order, as 3 to 2, or 3:2.
- I can also draw the ratio. On a tape diagram I give apple juice 3 equal parts and sparkling water 2 equal parts, so one batch is 5 parts in all.
- Those same 5 parts show a second ratio: apple juice to the whole fruit drink is 3 to 5.
- On a double number line I line the two amounts up: 5 cups of fruit drink pairs with 3 cups of apple juice, and 10 cups of fruit drink pairs with 6 cups of apple juice.
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 bowl has 4 apples and 1 orange. What two amounts are we comparing? We write apples to oranges in order: 4 to 1, or 4:1. Now draw it: 4 equal parts for apples beside 1 part for oranges, 5 parts of fruit in all. So apples to total fruit is 4 to 5. Now prove it: say why that move had to work at all — not just that it did.Show your work - 2
Warm restartWhat is the reciprocal of 3/4?
- A4/3
- B3/4
- C1/4
- D7/4
How do you know?
- 3
Warm restartWhat is 4 ÷ 1/2?
- A8
- B2
- C4 1/2
- D1/8
How do you know?
- 4
Warm restartWhat is 3/4 ÷ 1/2?
- A3/8
- B1 1/2
- C2/3
- D1/2
How do you know?
Practice Set · Part 2
Understand Ratios
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 throughKeeping the 3:2 ratio, how many main dishes go with 10 side dishes?
- A15
- B12
- C5
- D20
Why is that the answer?
- 6
Think it throughWhat kind of ratio is 3 mains to 2 sides?
- APart-to-part, because it compares two separate groups
- BPart-to-whole, because it compares mains to all dishes
- CA rate, because it uses different units
- DNot a ratio at all
How do you know? Give a second reason as well.
- 7
Think it throughWith 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
Explain your thinking. What would have to change for a different choice to be right?
- 8
Back to the modelWhat makes something a ratio? How did you decide which statements to sort into each group?
Practice Set · Part 3
Understand Ratios
Words and reasoning
Word bank · Banco de palabras
Use the words
Fill each blank with a word from the bank.
- A comparison of two quantities by division is a ___.
- A comparison of two quantities, like 3 to 5, is a ___.
- Showing how two amounts relate to each other is a ___.
- A ratio that compares one part of a group to another part is a ___ ratio.
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 Understand Ratios is writing the ratio in the wrong order: when asked for the ratio of apple juice to sparkling water in a recipe that uses 3 cups of apple juice for every 2 cups of sparkling water, some students write 2:3 (sparkling water to apple juice) because they list the ingredients in whatever order comes to mind rather than the order the question asks for. - 10
Say moreWhen you sorted the board statements, what made something a ratio instead of NOT a ratio (like '12 cookies on the tray')?
- 11
Write your ownWrite your own problem about this situation, then solve it and show the answer. The situation: The recipe card shows the ingredients needed to make one batch of sparkling cranberry-apple fruit drink.
Show your work
Practice Set · Part 4
Understand Ratios
Show what you know
Last check
These two come from Lesson 2.12. If they are shaky, that is the lesson to revisit — not this one.
- 12
Show what you knowExplain 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
Explain your choice.
- 13
From Lesson 2.12Explain your thinking — What is 4.6 × 2.3?
- A10.58
- B105.8
- C1.058
- D10.48
How do you know?
- 14
From Lesson 2.12A student answered $238.00. What went wrong?
- AThey put the decimal point in the wrong place
- BThey added instead of multiplying
- CThey rounded too early
- DThey used the wrong price
How do you know?
Be honest — this tells your teacher what to do next
| I can… | Not yet | Getting there | Got it |
|---|---|---|---|
| I can write and describe a ratio that compares two quantities, explain what each part stands for, and build one for a situation I have not seen before. | |||
| I can explain why it works: A ratio compares two quantities, and the order you write them in matters… | |||
| 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