This math topic focuses on the measurement of straight-line segments on a grid, each consisting of squares with sides of unit length. The problems involve determining which line segment matches specific lengths given that certain segments are labelled. This serves as an introduction to concepts of perimeter by guiding the learner to accurately measure lengths on a grid, a critical skill for understanding geometrical spaces and perimeter calculations. The questions challenge students to identify the correct line segment that corresponds to the stated length, enhancing spatial reasoning and accuracy in measurement.