Area & Perimeter - Find the Missing SidesThese anchor charts are helpful tools for teachers who want to help their students remember how to find the missing sides of a shape when given its area or perimeter and only one side length. To find the missing side, students use the information they already know.For area, students can divide the area by the known or given side length to get the missing side measurement.For the perimeter, students can add the lengths of the two known sides, subtract