It is ideal to have enough space so each of your child has its own bedroom. But what if you have just one bedroom and four kids? The best way out is opting for bunk beds that will accomodate all of your kids plus will help solving space issues.
Ok, so I know this is a bedroom but it's a great use of space for a small room. I particularly like the use of the dead space behind the ladder for shelving. It could also be a cool idea for a kids play room.