This one may be a bit on the feminine side but you can tweak it by using different colors of tissue paper.
*tissue or crepe paper
Grab a sheet of paper and cut a blobbish shape out of it about 6" round.
Punch 2 holes at opposite sides and add a length of knotted yarn to each hole.
Slather a party of glue all over the top of your paper shape.
Have your kiddos crumple, fold, and dollop small pieces of tissue or crepe paper into the glue. Crepe paper streamers work perfectly for this. Set aside to dry.
Once dry, plop atop the noggin and celebrate! How's that for ten hats in ten days? Which hat will you make for hat day? Send me a link or a photo and I'll post it here on the 'do!