Lesson objective: Apply understanding of composing and decomposing numbers to match equivalent values.

This lesson provides an opportunity for students to apply their knowledge and understanding of creating equivalent but easier problems to a real-life situation. Students are asked to find matching values for sums less than 20 as they play a matching game, *The Same Game*.

Key Concept students will use:

- We can use addition and subtraction facts we already know to help us solve addition and subtraction problems we haven't seen before.

Skills students will:

- Solve math facts to 20.
- Apply "make a ten" strategy to decompose and compose problems.
- Compose and decompose more difficult math facts to create easier but equivalent problems.
- Solve doubles, doubles +1, and doubles -1 math problems.

Students engage in Mathematical Practice #3 (Construct viable arguments and critique the reasoning of other) as they share their strategies for matching equivalent values while playing *The Same Game*.

**Key vocabulary: **

- compose
- decompose
- equivalent value
- sum

**Special materials needed:**