This math topic focuses primarily on calculating the length of various line segments represented on a grid of 1x1 squares. The problems engage students in identifying and verifying the lengths of lines within a grid by counting units, catering specifically to an introductory understanding of the concept of perimeter. The worksheet comprises multiple questions where students are to find line segments that equal specific lengths, such as 10, 12, 16, 11, and 8 units. This practice helps build foundational skills in understanding geometric shapes and measuring the lengths of lines on grids.