"From Figure 4 he sees a parallelogram equal to a rectangle of the same base and altitude. Cut out and…

"The student sees the trapezoid is equal in area to a rectangle whose base is the average base of the…

"The student sees the trapezoid is equal in area to a rectangle whose base is the average base of the…

A visual representation of cubing. "In the diagrams, Figure 1 represents 40 cubed and has a content…

The shaded region represents 5/8 of the rectangle. If II is divided in to thirds, then those pieces…

The shaded region represents 2/5 of rectangle. III can be compared to I and II to find that it is made…