Lesson objective: Solve problems involving addition and subtraction of whole numbers within 20.

This lesson provides an opportunity for students to apply their knowledge and understanding of addition and subtraction to a real-life situation. Students are asked to use a table listing bags of jelly beans and the number in each bag to solve addition and subtraction problems.

Key Concept students will use:

- We can count on or make ten to add and subtract within 20, and the total or difference stays the same regardless of the strategy we use.

Skills students will use:

- Compose and decompose numbers within 10. (K.OA.10 - Kindergarten, Units 10 and 16)
- Read and write numbers to 20. (K.CC.1 - Kindergarten Units 2 and 7)
- Find the sum of single digit numbers to 10. (K.OA.4 - Kindergarten, Units 4, 6, 10, and 16)
- Count on to 100 from a number other than 1. (K.CC.2 - Kindergarten, Unit 14)
- Add and subtract within 10. (K.OA.2 - Kindergarten, Unit 10)

Students engage in Mathematical Practice 1 (Students** **make sense of problems and persevere in solving them) as they examine a table and decide on the quantity of jelly beans to use to complete and solve additional and subtraction word problems.

**Key vocabulary: **

- add
- equals
- makes
- problem
- solve
- subtract

**Special materials needed:**

- counters or linking cubes