Students will be given 3 + 8 = 11 and tasked with 8 + 3 = __. They should also solve missing number problems. *For example, given 2 + 7 = 9, task them with 7 + __ = 9.*

Next, give your students these challenges:

- 2020 Math Kangaroo Levels 1-2 Problem #22 by STEM4all
- 2017 Math Kangaroo Levels 1-2 Problem #14 by STEM4all

Conclude by leading this investigation:

Speed Counting to Infinity

by MathPickle

1.OA.B.3: Apply properties of operations as strategies to add and subtract. Students need not use formal terms for these properties. *Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)*