Division Game Day

10 min

Narrative

The purpose of this Number Talk is to elicit the strategies and understandings students have for finding related quotients, which will be helpful later in this lesson when students divide within 100.

When students use the relationship between multiplication and division, along with known division facts, to find a division fact they don’t know, they look for and make use of structure (MP7).

Launch

  • Display one expression.
  • “Give me a signal when you have an answer and can explain how you got it.”
  • 1 minute: quiet think time
Teacher Instructions
  • Record answers and strategies.
  • Keep expressions and work displayed.
  • Repeat with each expression.

Student Task

Find the value of each expression mentally.

  • 48÷248\div2
  • 48÷348\div3
  • 48÷448\div4
  • 48÷648\div6

Sample Response

  • 24: Half of 48 is 24. 40 divided by 2 is 20, and 8 divided by 2 is 4, so 48 divided by 2 is 24.
  • 16: I know that 3×103\times10 is 30 and 3×63\times6 is 18, so 3 groups of 16 is 48.
  • 12: 40÷4=1040\div4=10. 8÷4=28\div4=2. 10+2=1210+2=12.
  • 8: I know that 5×85\times8 is 40. 1 more group of 8 would be 48, so that's 6 groups of 8.

Synthesis

  • “There are a lot of ways to divide 48. What are some other numbers that can be divided in many ways?” (24, because it can divided by 2 to get 12 or by 4 to get 6. 100, because it can be divided by 2, 4, 5, 10, 20, 25, or 50.)
Standards
Addressing
  • 3.OA.7·Fluently multiply and divide within 100, using strategies such as the relationship between multiplication and division (e.g., knowing that 8 × 5 = 40, one knows 40 ÷ 5 = 8) or properties of operations. By the end of Grade 3, know from memory all products of two one-digit numbers.
  • 3.OA.C.7·Fluently multiply and divide within 100, using strategies such as the relationship between multiplication and division (e.g., knowing that <span class="math">\(8 \times 5 = 40\)</span>, one knows <span class="math">\(40 \div 5 = 8\)</span>) or properties of operations. By the end of Grade 3, know from memory all products of two one-digit numbers.

15 min

20 min