Skill: area-perimeter
Area Explorer Lab
Drag the gold corner of the rectangle on grid paper. Watch area and perimeter update live —
then flip on the triangle overlay to see why triangles take half.
Grid paper
Drag the gold handle to resize. Each square is 1 × 1.
8
Length
5
Width
40
Area (squares)
26
Perimeter
Controls
Show the triangle half
The diagonal cuts the rectangle into two congruent triangles — each one is exactly half the area.