Lesson objective: Compare organized data using the relationship between addition and subtraction

This lesson helps to build fluency with comparison situations in relation to data collection. Number lines are used here because they support the understanding of how addition and subtraction are related. This work develops students' understanding of numbers and operations. By determining the distance between two numbers, students understand how these numbers are related.

Students engage in Mathematical Practice 1 (Make sense of problems and persevere in solving them) as they notice that they can use the properties of operations and the relationship between addition and subtraction to solve comparison situations from data using the number line.

**Key vocabulary:**

- addend
- addition
- category
- collect
- compare
- data
- graph
- greater than
- interpret
- key
- less
- less than
- missing addend
- more
- organize
- picture graph
- represent
- subtraction
- tally mark
- unknown number

**Special materials needed:**

- white boards/markers or paper/pencil
- number lines to 20