Paper boat construction... kids will love this.
Fun and simple games for kids
Straw Javelin Throw- a fun and simple boredom buster for kids
Mamas Like Me: Fun Water Games for Kids
DIY bean bag toss
Football Toss: Handmade Goal (see example above) made from a wood frame supporting a tire. Sidewalk Chalk (or other marking material) to draw lines for different aged players.