Side Lengths and Areas

In this video lesson, students learn about square roots. They examine a single line segment as it relates to two different figures: as a side length of a triangle and as a radius of a circle. They use this insight to estimate the side length of a square via a geometric construction that relates the side length of the square to a point on the number line and verify their estimate. Once students locate the side length of the square as a point on the number line, they are formally introduced to square roots and square root notation: is the length of a side of a square whose area is a square units. Finally, students use the graph of the function y = x² to estimate side lengths of squares with integer areas but non-integer side lengths.

Grade 8, Episode 22: Unit 8, Lesson 2 | Illustrative Math