In this Cyberchase video clip, Jackie finds a rectangular box that is in need of a top. She measures the box and notes that is 16 cyber-inches vertically and 18 cyber-inches horizontally. She mistakenly draws a rhombus with the same dimensions. Matt says it looks like the rectangle is "leaning" and they discover that a rectangle must have four ninty-degree corners. They use material that already has one perfectly square corner and a carpenter's ruler to re-draw the box top.