Rainy day. Bored children. Playdough!
1 cup flour
1 cup water
1 tsp cream of tartar
1/2 cup salt
dessert spoon sunflower oil (or similar)
Mix 'em all together on a low heat. Stir til it goes solid, then take it out and knead it a little to toughen it up. I recommend adding the food colouring during cooking, it's less messy, but if you want two colours, do seperate batches - the alternative is to poke holes in the finished playdough, pour in the colouring and gingerly knead - but you get stained hands and possibly surfaces.
It keeps well in a plastic bag in the fridge.
I love playdough.