They work just like bingo daubers, and Luke could easily use them. (Kimberly was sleeping, so I don't know how she will do) Luke learned the difference between "dotting" gently and "dotting" hard. He consistantly used them gently after a few tries.
One of my favorite craft websites is DLTK-Kids. On this site I found pictures to print out just for these markers. The printables have little circles for the child to "dot" on. The colors are very bright and Luke made no mess at all.
This is a product that we will be using over and over again during "toddler school".