# 2.7 Adding and Subtracting within 1,000

## Unit Goals

- Students use place value understanding, the relationship between addition and subtraction, and properties of operations to add and subtract within 1,000.

### Section A Goals

- Add and subtract numbers within 1,000 without composition or decomposition, and use strategies based on the relationship between addition and subtraction and the properties of operations.

### Section B Goals

- Add numbers within 1,000 using strategies based on place value understanding, including composing a ten or hundred.

### Section C Goals

- Subtract numbers within 1,000 using strategies based on place value understanding, including decomposing a ten or hundred.

### Glossary Entries

**a third**One piece of a shape split into 3 pieces that are the same size.

A third of the rectangle is shaded.

**bar graph**A way to show how many in each group or category using the length of rectangles.**centimeter**A length unit in the metric measurement system. There are 100 centimeters in a meter.

**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.**expanded form**A specific way of writing a number as a sum of hundreds, tens, and ones.

Expanded form writes a number as a sum of the value of each digit. Example: 482 written in expanded form is \(400 + 80 + 2\) .

**face**A flat side of a solid shape.**foot**A length unit in the U.S. customary measurement system.

There are 12 inches in a foot.

**hexagon**A shape with 6 sides and 6 corners.

**inch**A length unit in the U.S. customary measurement system.

There are 12 inches in a foot.

**line plot**A way to show how many of each measurement using an x for each measurement.**meter**A length unit in the metric measurement system.

There are 100 centimeters in a meter.

**number line**A diagram that represents numbers as lengths from 0 using equally spaced tick marks or points.

**pentagon**A shape with 5 sides and 5 corners.**picture graph**A way to show how many in each group or category using pictures of the objects or symbols.**quadrilateral**A shape with 4 sides and 4 corners.**thirds**The pieces created when a shape is split into 3 pieces that are the same size.

This circle is split into thirds.