Dictionary Study For 7yrs-old!?

Obviously now it's getting popular in Japan. 7yrs-old, that's the age when they start to learn to read 'kana'. So according to the topic, just let kids to use a dictionary for anything, for instance, they had an orange for lunch, then look up for 'orange' in a dictionary. And every single word they take, they have to put a sticky note. When they have 500, or even 1000 sticky notes on their dictionary, they get a prize. I mean, it sounds kinda good... Well, it sounds fun... But, does it work for our kids with English dictionary? Well... Why not... Right? John will be 6 in this summer, maybe I can let him start that with my help...?