Perimeters using a rectangular grid worksheets | K5 Learning Worksheets Math Grade 3 Geometry Perimeters & grids Perimeters using a rectangular grid Counting squares to find perimeters A perimeter is the length of the outline of a shape. In these worksheets, students find the perimeter of rectangular shapes by using a grid . Worksheet #1 Worksheet #2 Irregular, inches Worksheet #3 Worksheet #4 Irregular, cm