...then it's time to drop your lesson plans and cook eggs on a sidewalk.
I got tired of looking at zombie-eyed students so I divided them into groups, gave them a square of foil and an egg, and sent them outside. I told them they had 20 minutes to cook the egg. They could put the egg and arrange the foil anywhere they wanted.
Twenty minutes later we came out to check on the eggs. Only a few of them had started cooking the whites. Perhaps our egg experiment was a flop, but it was a good way to get out and enjoy the breeze!