continue to clean up after the kittens until you start them on solid foods. This is when I let the mom teach them about the litter box. I use a box from a case of soda to train them in as it is easier to climb into. Mom usually does a great job of teaching them. Make sure to keep the kittens until they are 12 weeks so they get all the socialization skills they will need before getting seperated from mom. You will also know they are completly covered by their kitten shots so they won't become ill.