# Area and perimeter

Contents

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.

Try some practice problems

Learn by doing or check your understanding

Find area of shapes by counting unit squares. Some shapes will require combining partial square units to find area. Create rectangles with a given area by covering unit squares.

Transition from counting unit squares to multiplying side length to find area. Measure side lengths with a ruler to find area. Find area of rectangles by multiplying side lengths. Find a missing side length of a rectangle when given the other side length and area.

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 what perimeter is and how to calculate it.

Understand the formula for the area of a parallelogram.

Understand the formula for the area of a triangle.

Area problems involving triangles and quadrilaterals on grids

Finding the area of more complex shapes like trapezoids and composite figures (shapes built from other shapes)

A circle is at the foundation of geometry, and at the foundation of a circle is a special number called Pi. This number allows us to relate the radius, diameter, and circumference of a circle.