This topic is in the 'Perimeter, Area and Volume' section. You'll see some general tutorials about what perimeter, area, and volume mean, and then you'll be able to dive into some details related to specific shapes like triangles, rectangles, squares, parallelograms, trapezoids, and circles. You'll also be able to learn about the volumes and surface areas of the 3D versions of these shapes. In the end you'll have a good feel for a lot of the classic geometry formulas that you'll see on your tests and homework. We try to give you a good sense of why the formulas work the way that they do, but to fully understand where these formulas come from, you'll probably have to wait until Calculus, where you'll be expected to derive some of these formulas from scratch. So keep in mind what you have to look forward to several years from now:)