As several people have recommended, you should consider getting some of your kids training done at home. However, this is not madatory by any means. It only takes 3 days to get certified on Utila. Kids learn very fast and I think make great students. Some seem to be born fishes and I've found most follow the rules and instructions very well. If you can find instruction at home, don't want to pay the price, or just find in inconvenient, don't worry about it. Just enjoy the trip and have fun. It's not worth losing any sleep over it.