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. The game Fish Bowl is used here because it gives students a real life representation of known and unknown numbers. This work 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:**

- determine
- equation
- missing
- model
- represent
- symbol
- true
- unknown
- value

**Special materials needed:**

- counters
- cubes
- Fish Bowl cards