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.)
Area is how we think about how much space something takes in two dimensions, such as comparing how much land one property takes up versus another. In this tutorial, we'll take a conceptual look at how area is actually measured (especially for rectangles).
Have you ever wondered how much fencing you need to surround a plot of land? No? Well, you should still go through this tutorial just in case. You'll learn all about how to think about and calculate perimeter--essentially the length of the boundary of a figure.