This Basic geometry and measurement course is a refresher of length, area, perimeter, volume, angle measure, and transformations of 2D and 3D figures. If you are learning the content for the first time, …

Explore geometry concepts including angles, shapes, transformations, and proofs with Khan Academy's engaging resources.

Explore key 7th‑grade math skills aligned with New York’s Next Generation standards, including ratio reasoning, proportional relationships, integer operations, expressions, equations, and geometry.

Learn high school geometry—transformations, congruence, similarity, trigonometry, analytic geometry, and more (aligned with Common Core standards).

Created by experts, Khan Academy’s library of trusted, standards-aligned practice and lessons covers math K-12 through early college, grammar, science, history, AP®, SAT®, and more.

Area and perimeter help us measure the size of 2D shapes. We’ll start with the area and perimeter of rectangles. From there, we’ll tackle trickier shapes, such as triangles and circles.

This Arithmetic course is a refresher of place value and operations (addition, subtraction, division, multiplication, and exponents) for whole numbers, fractions, decimals, and integers. If you are …

Learn pre-algebra—all of the basic arithmetic and geometry skills needed for algebra.

Unit 8: Equations and geometry Unit mastery: 0% Equations & geometry Triangle angles Pythagorean theorem Triangle similarity intro Solving similar triangles

Learn algebra—variables, equations, functions, graphs, and more.