A water bed can be a lot of fun. It is a very big bag that’s filled with water. The water can be made nice and warm. You move up and down as the water moves. It’s something like being on a boat. It rocks you to sleep.A cot is a very light bed. When it’s not being used, you can fold it up and put it out of the way. Then you can take it out again when you need it. You can use it for a friend. A cot is just right for someone who is sleeping over,In some places people sleep on mats. The mats are made of long pieces of grass. People take them out at night on the floor. In the morning people take them up off the floor and roll them up. Think of how much room a house has with no beds!