Lesson 13: Expression with Exponents

Expressions with Exponents

Lesson # 13

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2019 Open Up Resources |

Let’s use the meaning
of exponents to decide if equations are true.

Today’s Goals

• I can decide if expressions with exponents are equal by evaluating the expressions or by understanding what exponents mean.

Which One Doesn’t Belong: Twos

Warm Up

Which one doesn’t belong?

Is the Equation True?

Activity 1
● MLR8: Discussion Supports

Drag and Drop

Is 4² = 2³ true?​ ​

Placeholder

Drag these tiles and drop them in the correct blank above

False

I don't know

True

Multiple Select

Select all expressions that are equal to 3⋅3⋅3⋅3⋅3.

• 3⁵

• 3⋅5

• 3⁴⋅3

• 5³

Multiple Choice

Decide whether the equation is true or false. $$7+7+7=3+3+3+3+3+3+3$$

• true
• false

Multiple Choice

$$6+6+6=6^3$$

• True

• False

Let’s Talk About It

●Can you switch the order with exponents like we can with addition and
multiplication—specifically, are ab and ba equivalent? How do you know?

●What change can we make to the equation 3+3+3+3+3=35 to make it true?

●Your friend claims the equation ½ ᐧ ½ ᐧ ½ ᐧ ½ = 4 ᐧ ½ is true. What do you think they are
misunderstanding? How can you convince them it is false?

●Can you show that 82 = 43 is true without evaluating both sides? What understanding about
the meaning of exponents and operations can help you?

What’s Your Reason?

Activity 2
● MLR8: Discussion Supports

Work with your partner (10 min)

Lesson Synthesis

Lesson Synthesis

Coin Calculation

Cool Down

Open Ended

Andre and Elena knew that after 28 days they would have 2²⁸ coins, but they wanted to find out how many coins that actually is. Andre wrote:

$$2^{28}\ =\ 2\ \cdot\ 28\ =\ 56$$

Elena said, “No, exponents mean repeated multiplication. It should be $$28\cdot28$$ , which works out to be 784.” Do you agree with either of them? Explain your reasoning.