Geometry

This course is a part of 4th grade, a 17-course Topic series from Khan Academy.

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!

This course contains 11 segments:

Lines, line segments, and rays

Let's draw points, lines, line segments, and rays. We'll also think about perpendicular and parallel lines and identify these in two-dimensional figures. Common Core Standard: 4.G.A.1

Parallel and perpendicular

Learn the definitions of "parallel" and "perpendicular".

Angle introduction

What is an angle and how do we label, measure and construct them? Great question. Luckily we have all your answers! To begin our journey towards understanding angles, we'll learn terms like vertex, acute, obtuse, circle arc, circumference, and protractor. These basic angle concepts will get you on the road to angle domination!

Measuring angles

Learn how to measure angles using a protractor.

Constructing angles

Learn how to draw angles using a protractor.

Angles in circles

Learn how to measure angles using a circle protractor and solve word problems about angles as part of a circle.

Angle types

Now that we know what angles are, let's dig a bit deeper and classify them and understand their properties better. Acute, obtuse, right, adjacent--all are angles that we will be become familiar with.

Decomposing angles

Learn to combine angles and take them apart to create new angles.

Line of symmetry

A line of symmetry for a two-dimensional figure is a line across the figure such that the figure can be folded along the line into matching parts. In this tutorial, we'll identify line-symmetric figures and draw lines of symmetry. Common Core Standard: 4.G.A.3

Classifying triangles

Triangles can be classified in different ways. In this tutorial, we'll learn about scalene, isosceles, equilateral, acute, right, and obtuse triangles.

Classifying geometric shapes

Some practice classifying geometric shapes.