Simple springtime entertainment.
I make it a goal to find a way to get the kids outside, even for a short while, every day. Sidewalk chalk, finding rocks, chasing grass hoppers, going for a walk, or flying a kite. When it's too cold in the winter, it means just going for a ride in the car some place. The point is, kids need a little sunlight and a change of scenery for healthy stimulation.
You can get a good kite for $10-15 or a cheap one for about $3.