The Locker Problem

10 min

Narrative

The purpose of this Choral Count is for students to practice counting by 2 and 4 and notice common multiples of the two numbers in the count. Students may notice that the count by 4 is every other number in the count by 2. The relationship between the two counts can also be described using multiplication which is the goal of the Activity Synthesis.

Launch

  • “Count by 2, starting at 0.”
  • Record as students count.
  • Stop counting and recording at 30.
  • Count by 4, starting at 0.
  • Record as students count.
  • Stop counting and recording at 60.
Teacher Instructions
  • “What patterns do you see?”
  • 1–2 minutes: quiet think time
  • Record responses.

Sample Response

  • Record the first count in a column with the title “count by 2.” Record the second count next to the first with the title “count by 4.”

Sample responses:

  • Pattern in counting by 2s:
    • The numbers in the ones place repeat 2, 4, 6, 8, 0, 2, 4, 6, 8, 0.
  • Pattern in counting by 4s:
    • The numbers in the ones place repeat 4, 8, 2, 6, 0, 4, 8, 2, 6, 0.
  • Patterns between the two counts:
    • The second list is included in the first list.
    • Every other number in the first list is in the second list.
    • Each number in the second list is twice the corresponding number in the first list.
    • Each number in the first list is half the corresponding number in the second list.
Activity Synthesis (Teacher Notes)
  • “How can I get the number in the second list from the corresponding number in the first list?” (Double the number by adding it to itself or multiplying the number by 2.)
  • “How can I get the number in the first list from the corresponding number in the second list?” (I can take half of the number or divide the number by 2.)
Standards
Addressing
  • 4.OA.B·Gain familiarity with factors and multiples.
  • 4.OA.B·Gain familiarity with factors and multiples.

10 min

25 min