Chub Angler,
At 7 and 8 your children are easily old enough to start fishing.
My advice would be to get them each a 3 or 4m whip with a simple float set-up and teach them on a venue where they are likely to actually catch something. There is nothing worse than having them being bored as they are not catching.
Linda's idea about some crayons and paper is a good one, if they get bored they can draw pictures of the river/lake etc.
Good luck with them, my own children started when they were 5 years of age, the eldest never took it up, prefering cricket, but the youngestbecame anestablished Carp angler - they are now bith in their 30's.