Expressions with Exponents

5 min

Narrative

This Warm-up prompts students to compare four expressions. It gives students a reason to use language precisely (MP6). It gives the teacher an opportunity to hear how students use terminology and talk about characteristics of the items in comparison to one another.

Launch

Arrange students in groups of 2–4. Display the expressions for all to see. Give students 1 minute of quiet think time and ask them to indicate when they have noticed three expressions that go together and can explain why. Next, tell students to share their response with their group and then together find as many sets of three as they can.

Student Task

Which three go together? Why do they go together?

  1. 2⋅2⋅2⋅22 \boldcdot 2 \boldcdot 2 \boldcdot 2
  2. 1616
  3. 242^4
  4. 4⋅24 \boldcdot 2

Sample Response

Sample responses:

A, B, and C go together because:
  • They are equivalent expressions.
  • They are equal to 16.
A, B, and D go together because:
  • They don't use exponents.
A, C, and D go together because:
  • They represent multiplication.
  • They show 2 and 4. (C and D show the numbers, and A shows 4 twos.)
B, C, and D go together because:
  • They each use only 2 numbers or digits.

Synthesis

Invite each group to share one reason why a particular set of three go together. Record and display the responses for all to see. After each response, ask the class if they agree or disagree. Since there is no single correct answer to the question of which three go together, attend to students’ explanations, and ensure the reasons given are correct.

During the discussion, prompt students to explain the meaning of any terminology they use, such as “numbers,” “digits,” or “exponents,” and to clarify their reasoning as needed. Consider asking:

  • “How do you know . . . ?”
  • “What do you mean by . . . ?”
  • “Can you say that in another way?”
Standards
Addressing
  • 6.EE.1·Write and evaluate numerical expressions involving whole-number exponents.
  • 6.EE.A.1·Write and evaluate numerical expressions involving whole-number exponents.

15 min

15 min