Different Ways to Solve Problems

10 min

Narrative

This Warm-up prompts students to carefully analyze and compare features of expressions. In making comparisons, students have a reason to use language precisely. The activity also enables the teacher to gain insight into students’ understanding of properties of operations and how they talk about them. This activity prepares students to reason flexibly and to use multiple strategies (including writing different expressions) to solve word problems later in the lesson.

Launch

  • Groups of 2
  • Display expressions.
  • “Pick 3 that go together. Be ready to share why they go together.”
  • 1 minute: quiet think time
Teacher Instructions
  • “Discuss your thinking with your partner.”
  • 2–3 minutes: partner discussion
  • Record responses.

Student Task

Which 3 go together?

A

5×905 \times 90

B

90+90+90+90+9090 + 90 + 90 + 90 + 90

C

(4×90)+(1×90)(4 \times 90) + (1 \times 90)

D

3×3×10×53 \times 3 \times 10 \times 5

Sample Response

Sample responses:

A, B, and C go together because:

  • They have 90.
  • The value is equal to 450.

A, B, and D go together because:

  • Each has only one type of operation symbol.

A, C, and D go together because:

  • They have a multiplication symbol.

B, C, and D go together because:

  • They have multiple operations.
Activity Synthesis (Teacher Notes)
  • “Why do all 4 go together?”(They all have a value of 450.)
  • “Can you write another expression that has the same value as these expressions but that doesn’t belong?”
Standards
Addressing
  • 4.OA.A·Use the four operations with whole numbers to solve problems.
  • 4.OA.A·Use the four operations with whole numbers to solve problems.

20 min

15 min