This would be great for practicing addition skills. How to make a unique bean bag toss game from terra cotta pot saucers and a printable (which you can get for free by clicking through!) (Diy Crafts For School)
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!
Teds Woodworking - DIY Projects - Outdoor Games - DIY Giant Backyard KerPlunk Game Tutorial - fun for barbecues - cookouts - backyard birthday parties DIY Tutorial via allParenting - Projects You Can Start Building Today