I have a mother cat who is 1 and 6 4 week old kittens. The are in an enclosed area so i can lock the mother in with them at night time, and during the day i take the top off and she can get out. Anyway, the mother has started sleeping on the roof during the day, and the kittens have started sleeping in the new kitty litter tray. They have a box that they sleep in at night, but in the day i take it out so they have more room to play and i just leave there blanket in the house, and that was fine, but i have now added a litter tray for them to experiment with, and at first they ate it, and now they are sleeping in it. How do i get them to realise that it is for peeing in? The mother doesn't seem interested in showing them how to go to the toilet as she has a separate box and in the day i take it out otherwise they play in it.