Lesson objective: Apply understandings of symbols within equations and the meaning of the equals sign to find unknown numbers and create true equations.

This lesson helps to build fluency with finding unknown numbers in equations. Two-sided counters are used here to give students a visual representation of the numbers given in each equation. This work develops students' ability to find unknown numbers. It also develops students' understanding that symbols can be used to represent unknown numbers in equations.

Students engage in Mathematical Practice #4 (model with mathematics) as they determine the meaning and value of symbols and use addition strategies to justify their reasoning.

**Key vocabulary:**

- equation
- missing
- symbol
- true
- unknown

**Special materials needed:**

- counters
- cubes
- number cards