Dave
The loon might struggle with a longer 7wt, i started Daniel fly fishing with a 7ft 5/6wt, that he could manage no probs at 5, he has since progressed to a 8ft6 5/6 that he bought himself and has used this since 8, he loves it and his casting has slowly got better, he puts out a lovely line now and regularly catches more than me
The best thing though is to take them fishing, not take them fishing with you, if you see what i mean, I only had daniel fishing for the first couple of years and when he got fed up after an hour or so we went home, when he caught fish we seemed to stay for 2-3hrs before getting bored. To start with i asked if he wanted to go and only went when he said yes (otherwise i fished on me own) fairly soon he was asking to go, after about a year and a half of him fishing, he wanted me to fish too, the rest as they say is history, I now have a great boat partner, incidently he finds it much easier to fish from the boat than from the bank, Mike's boats are really stable.
The clear intermediate mike does is as good as the best on the market, and much better value
I'll ask daniel if he wants to lend you his old rod for the bairn, he never uses it now and might be happy to lend it for a while to see if he enjoys it.
Sandy