Mastering French very well, I offer your children support lessons in order to improve their level. I would adapt to each child (his age, his level, his preferences, his shortcomings ...) Together we will do exercises, we will play games to learn new words, we will work on pronunciation, grammar, conjugation, syntax etc. Depending on his age, I would also suggest book titles for him to read and summarize. I would give him homework to do that we will correct later. I would try to diversify the activities as much as possible, so your child will not be bored and will continue to learn with joy and good humor.