Spring chalk art: Have students work together in groups: brainstorm and sketch inside, then use a class period to draw w/ chalk on blacktop, then pose together laying on blacktop. I stand on a ladder and take their pictures!
Make a backyard bowling alley. Add food coloring to clear plastic bottles of water. Use party streamers as lane margins. Add glow sticks for night bowling. (These would make great outdoor table nightlights also with the glowsticks, gonna try it!