ClipArt ETC
"From Figure 4 he sees a parallelogram equal to a rectangle of the same base and altitude. Cut out and paste in rectangle form." -Foster, 1921

Area of Parallelogram

"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 trapezoid, and whose altitude is the same as that of the trapezoid." -Foster, 1921

Area of Trapezoid

"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 trapezoid, and whose altitude is the same as that of the trapezoid." -Foster, 1921

Area of Trapezoid

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