Algebra Number of players: 2 Materials: Spinners, index cards

Shed Some Light on Parabolas

Copy onto cards the equations shown below, one per card. Shuffle the cards and place them face down in a pile. Label equal sections of two spinners "-6," "-4," "-3," "-1," "0," "2," "5," "6." Decide which spinner names x-coordinates and which spinner represents y-coordinates.

If you lay a flashlight down on a sheet of paper, the beam it casts on the paper suggests a parabola. (Try it some time.)

One partner spins both spinners and plots the point named on a coordinate grid. The other partner selects the top card from the pile and graphs the quadratic function. If the first partner's point lies withing the resulting "beam" (parabola), the partner who graphed the quadratic function gets 1 point. If the point is outside the "beam" (parabola), the partner who plotted the point gets 1 point. Trade roles and repeat the activity. Continue until all the cards have been selected. The partner with the most points wins.

Quadratic functions to put on cards:
y = -x2 + 5	y = 1 - 2x2
y = x2 + 3	y = 4x2 - 12	y = 1.5x2
y = x2	y = 3x2 + 20
y = -2 - x2