# 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!

#### Fractions

In 3rd grade, you got a basic conceptual understanding of what a fraction is. Awesome. Now we dig deeper by comparing fractions and starting to perform operations on them. We also see how they relate to decimals. Some of the skills we'll cover here include visualizing equivalent fractions; comparing, adding (with like and unlike denominators), subtracting, and decomposing fractions; adding, subtracting and changing mixed numbers; changing improper fractions; multiplying whole numbers and fractions; and rewriting fractions as 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!

#### 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 is here to get familiar with the basic concepts, skills, and applications of geometry. So jump in and let's go for a ride!

#### 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 value for several years now, but now we make sure that we **really** get how one place relates to another. We then use this deep understanding for understanding the conventions for rounding.