Group Activity Cards
Use groups of 3.
Materials: Spinners, centimeter grid paper, metric rulers, index cards
| Trapezoid Trios
Copy onto cards the following descriptions, one per card: one right angle, one obtuse angle, and two acute angles. Thoroughly mix the three cards. Label the sections of each of two spinners "3," "4," "5," "6," "7," "8." The numbers on these spinners represent the lengths in centimeters of bases of trapezoids. Label equal sections of a third spinner "3," "4," "5." These numbers represent the heights of trapezoids.
Each group member spins a spinner. Then each group member selects a card and draws a trapezoid with the height and bases shown on the spinners and the angle(s) described on the card. Finally, each group member computes the area of his or her trapezoid and shares his or her work with the group.
Repeat the activity and then, as a group, write what you have observed about the areas and shapes of trapezoids.