Practice Set · Part 1
Write and Evaluate Numerical Expressions with Exponents
Pick up where we left off
Where we left off
Our goal: I can write numerical expressions from a real situation and evaluate them using the order of operations, including powers, explain what each part stands for, and build one for a situation I have not seen before.
The big idea: Parentheses come first, then powers, then multiply and divide, then add and subtract, so where you put parentheses can change the value.
Model to copy — Example · Split a bill
- Seven friends split a bill. They order 4 pizzas at 3² dollars each, plus a $6 delivery fee. Write one expression for each friend's share. Evaluate it.
- Write the total bill: 4 × 3² + 6
- Put the total in parentheses. Then divide by 7: (4 × 3² + 6) ÷ 7
- Find the power first: (4 × 9 + 6) ÷ 7
- Work inside the parentheses. Then divide: (36 + 6) ÷ 7 = 42 ÷ 7 = 6
- (4 × 3² + 6) ÷ 7 = 6. Each friend pays $6.
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: Each student ticket costs 2³ dollars. Evaluate 2 × 15 + 4 × 20 + 8 × 2³. Find the power. Then do each multiplication. (2³ is 8 → 30 + 80 + 64) Add. What is the total? (30 + 80 + 64 = 174) Why must you find 2³ before you multiply by 8? (The exponent belongs only to the 2. So 8 × 2³ means 8 × 8 = 64, not 8 × 2 × 3.)Show your work - 2
Warm restartWhat is the value of 6²?
- A8
- B12
- C36
- D62
How do you know?
- 3
Warm restartWhat is the value of 4³?
- A7
- B12
- C43
- D64
How do you know?
- 4
Warm restartIn 2⁵, which number is the base and which is the exponent?
- ABase 2, exponent 5
- BBase 2, exponent 2
- CBase 5, exponent 2
- DBase 5, exponent 5
How do you know?
Practice Set · Part 2
Write and Evaluate Numerical Expressions with Exponents
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 2.50 + 1.75(8)?
- A4.25
- B14.00
- C16.50
- D34.00
Why is that the answer?
- 6
Think it throughWhat does the 2.50 represent?
- AThe cost of one mile
- BA flat base fee charged no matter how far you go
- CThe number of miles
- DThe tip
How do you know? Give a second reason as well.
- 7
Think it throughWhat does the 1.75 represent?
- AThe base fee
- BThe total cost
- CThe number of miles
- DThe cost per mile, multiplied by the number of miles
Explain your thinking. What would have to change for a different choice to be right?
- 8
Back to the modelTwo students evaluate 3 + 4 × 2 and get 14 and 11. Which one followed the order of operations, and why does the order have to be agreed on at all?
Sort it again — on paper this time
Write the letter of the group each one belongs in.
- 2² = 4
- 4 × 4 = 16
- 3 + 16 − 6 = 13
- Handle the exponent before anything else here
- Multiplication comes before addition
- Work left to right at the end
Practice Set · Part 3
Write and Evaluate Numerical Expressions with Exponents
Words and reasoning
Word bank · Banco de palabras
Use the words
Fill each blank with a word from the bank.
- Numbers and operations with no equal sign and no variable form a ___ ___.
- To put numbers in for the letters and work out the value is to ___.
- Grouping symbols, then ___, then × and ÷, then + and −.
- A number written with a base and an exponent, like 2³, is a ___.
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 with powers is multiplying the base by the exponent: reading 3² as 3 × 2 = 6 instead of 3 × 3 = 9. - 10
Say moreWhen you evaluate an expression like 4x² + 3, what order do you follow, and why must you square before you multiply?
- 11
Write your ownWrite your own problem about this situation, then solve it and show the answer. The situation: You are the music producer from the story. Your concert cost is given by the expression 150 + 12s, where s is the number of speakers you rent.
Show your work
Practice Set · Part 4
Write and Evaluate Numerical Expressions with Exponents
Show what you know
Last check
These two come from Lesson 6.3. If they are shaky, that is the lesson to revisit — not this one.
- 12
Show what you knowExplain your thinking — Evaluate 2 × 15 + 8 × 2³.
- A94
- B124
- C150
- D736
Explain your choice.
- 13
From Lesson 6.3Explain your thinking — What is the value of 3⁴?
- A12
- B34
- C64
- D81
How do you know?
- 14
From Lesson 6.3Why does the file grow so quickly?
- ABecause 4 MB is already large
- BBecause 5 is a big exponent
- CBecause the studio records faster each time
- DBecause each layer doubles the size instead of adding a fixed amount
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 numerical expressions from a real situation and evaluate them using the order of operations, including powers, explain what each part stands for, and build one for a situation I have not seen before. | |||
| I can explain why it works: Parentheses come first, then powers, then multiply and divide, then add and subtract… | |||
| 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