Build a Den Outdoors
Branches, a sheet, and a structure that has to actually stand up.
Not a snowman. Anything but a snowman.
One rule makes a snow day far more interesting than it would otherwise be.
Removing the default option forces actual invention, and the constraint does more for creativity than any amount of encouragement. Snow also collapses constantly, which makes structural problem-solving unavoidable.
Waterproof gloves and a firm time limit. Watch for numb fingers, and come in before anyone is genuinely cold.
Wet clothes straight onto a radiator.
Branches, a sheet, and a structure that has to actually stand up.
A big box, some tape, and no instructions whatsoever.
Tape a huge sheet of paper to the floor and let them draw on their hands and knees.
Music on, dance. Music off, freeze. That is the whole game.
A pillowcase each and a finish line down the hallway.
A potato on a spoon and a very slow, very serious walk down the hall.