I have taught many, many kids to kayak and some as young as 6 or 7 and the ones that are able to roll a kayak by age 7 or 8 are a pretty rare case. They just dont seem to have the body awareness or mechanic's to pull it off. I have also found that pushing them is going to make them apprehensive about going boating or roll practice. When kids see other kids out rolling and splashing around having a blast then you will see the twinkle in there eye. Bring your little one by class in Lyons on Tuesday's or Thursday's at 5:00pm to let him watch, and I bet he will be full of questions on the way home.
Jason