California Assessment of Student Performance and Progress (CAASPP) Math Practice Exam 2026 - Free CAASPP Math Practice Questions and Study Guide

Perimeter is best defined as the total distance around a closed figure. It represents the sum of the lengths of all the sides of a geometric shape. For example, if you have a rectangle, calculating the perimeter involves adding together the lengths of all four sides. This measurement reflects the boundary of the shape, providing an understanding of the distance you would need to travel to go completely around it.

The other options refer to different concepts in geometry. The area defined by the figure's interior pertains to how much space is encompassed within the shape, not the distance around it. The length of one side of a polygon represents only a part of what constitutes the perimeter, as you need to consider all sides. Lastly, the angle measurement of a shape describes the relationship between two lines meeting at a point but does not pertain to the distance around the shape. Thus, the total distance around a closed figure accurately encapsulates the definition of perimeter.