# 2.2 Adding and Subtracting within 100

## Unit Goals

• Students add and subtract within 100 using strategies based on place value, properties of operations, and the relationship between addition and subtraction. They then use what they know to solve story problems.

### Section A Goals

• Add and subtract within 100 using strategies based on place value and the relationship between addition and subtraction. Problems in this section are limited to the problems like 65 – 23, where decomposing a ten is not required.

### Section B Goals

• Subtract within 100 using strategies based on place value, including decomposing a ten, and the properties of operations.

### Section C Goals

• Represent and solve one- and two-step problems involving addition and subtraction within 100, including different problem types with unknowns in all positions.

### Glossary Entries

• bar graph
A way to show how many in each group or category using the length of rectangles.

• compose
To make a new unit from 10 of the next smallest unit. For example, compose a ten from 10 ones.

• data
Information about the things or people in a group.

Example: If you have a box of colored pencils, then the lengths and colors of each of the pencils are data about the pencils in the box.

• decompose
To break a unit into 10 of the next smallest unit.  For example, decompose a ten into 10 ones.

• picture graph
A way to show how many in each group or category using pictures of the objects or symbols.