# 3rd grade (U.S.)

3rd grade is full of some of the most important ideas in mathematics. You'll extend the addition and subtraction that you did in second grade to more than two digits. You will also get your first exposure to the ideas of multiplication, division, and fractions, which will be used the rest of your mathematical lives (we'll even use some letters as placeholders for unknown numbers along the way). 3rd grade is also when we first think about area (how much "space" something takes on a surface) and perimeter (the distance around a shape). All of that will be rounded out by making sure that you can apply these ideas in the real world and see patterns in the mathematical world. (Content was selected for this grade level based on a typical curriculum in the United States.)

#### Addition and subtraction

In the 2nd grade you learned to add and subtract 2-digit numbers. Now we take things further by adding and subtracting three-digit numbers. This is good practice for 4th grade where you'll be expected to add or subtract pretty much any whole number!

#### Multiplication and division

Multiplication and division are two of the most important operations to understand in math. If you drink 2 cups of water, 5 times, how much water have you drunk? If you need to divide 9 slices of cake between 3 friends, how much cake does each friend get?

#### Fractions

This will be your first introduction to the idea of fractions. You'll learn what they are and what they can represent. Then in 4th and 5th grades, you'll learn to compute with them.

#### Measurement and geometry

In 2nd grade, you learned to measure lengths. Now we can measure the length around the edge of an object (perimeter) and how much "space" something takes up on a flat surface (area).

#### Place value and rounding

Going a bit deeper with our understanding of place value from 2nd grade. We'll apply this knowledge to learn to round things to the nearest 10 and 100.

#### Expressions and patterns

We'll cover a few odds and ends here. In particular, you'll see whether order matters when you multiply and divide. We'll also explore some mathematical patterns.