# 4th grade (U.S.)

4th grade is the time to start really fine-tuning your arithmetic skills. Not only will you be a multi-digit addition and subtraction rockstar, but you'll extend the multiplication and division that you started in 3rd grade to several digits. You'll also discover that you sometimes have something left over (called a "remainder") when you divide. In 3rd grade you learned what a fraction is. Now you'll start adding, subtracting, multiplying, and comparing them. You'll also see how they relate to decimals. On other fronts, you'll learn how to convert between different units (which is super important when comparing the size and speed of robot unicorns in different countries) and continue your journey thinking about various shapes in two dimensions. Some of the foundational concepts of geometry (like lines, rays and angles) also get introduced. As always, we'll round this out with a healthy dose of applied word problems and explorations of number patterns and properties (including the ideas of factors, multiples and prime numbers). The fun must not stop! (Content was selected for this grade level based on a typical curriculum in the United States.)

## Addition and subtraction

Fourth grade is the time to really fine-tune your addition and subtraction skills to the point that you can add and subtract pretty much any multi-digit, whole number!

## Multiplication and division

Let's continue on the multiplication and division adventure that was started in third grade. We'll think about multiplying and dividing with whole numbers and discover that sometimes we have a leftover, or a remainder, when we divide. These tutorials will also help you get comfortable with multiplying multi-digit numbers, long division, and solving word problems. Let's do this people!

- Multiplication by tens, hundreds, and thousands
- Multiplication: place value and area models
- Multi-digit multiplication
- Comparing with multiplication
- Division problems that work out nicely
- Division: place value and area

## Fractions

Learn how to do basic arithmetic with fractions (add, subtract, and multiply). Also learn about mixed numbers and equivalent fractions, and use this knowledge to compare fractions with unlike denominators.

- Equivalent fractions
- Common denominators
- Comparing fractions with unlike denominators visually
- Comparing fractions with unlike denominators
- Decomposing fractions
- Adding and subtracting fractions with like denominators

## Decimals

Learn what decimal numbers are, and see how decimals are related to fractions. Along the way, find decimals on the number line, convert between fractions and decimals, and compare decimals.

- Introduction to decimals
- Decimals on the number line
- Decimals vs. fractions
- Decimals greater than one
- Converting decimals to fractions
- Common fractions and decimals

## Measurement and data

When we measure anything, we do it in human-defined 'units'. Different units were defined in different places and for different scales. The two most common are U.S. customary units and metric units. Let's think about how to convert between and among them! We'll also continue thinking about perimeter and area!

- Estimating mass
- Estimating volume
- Estimating length
- Estimating time
- Converting units of mass
- Converting units of volume

## Geometry

Finally, we're getting to geometry. We've been waiting for this and hope you have been, too. The foundation of all geometry is the line--so that's a great place to start. From there we'll move into angles, quadrilaterals, and triangles. Our goal here is to get familiar with the basic concepts, skills, and applications of geometry. So jump in and let's go for a ride!

- Basic geometry: lines, line segments and rays
- Parallel and perpendicular
- Angle introduction
- Measuring angles
- Constructing angles
- Angles in circles

## Factors, multiples and patterns

We know that 3x2x5 = 30. So 2, 3, and 5 are factors of 30. 30 is a multiple of each of 3, 2, and 5. If a number only has itself and 1 as factors, then the number is "prime". Don't worry, this is explained in much more depth in the tutorials in this topic. We will also explore some mathematical patterns.

## Place value and rounding

We've been exploring place for a while, thinking about ones, tens, and hundreds. But now we're ready to tackle all whole numbers, including numbers in the thousands, millions, and beyond!