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Teaching children Dutch
Sports camps run by this organisation in Overijse.
http://www.sporeo.be/welkom/
I really wouldn't go for too much emphasis on just the language camps, even our local ASBL which does Dutch, does it in combination with sport. Sorry don't have a clue where to look for an equivalent near Genval, I'm sure there'll be something similar to this though at Institut Don Bosco in SPW (but these ones don't start until 7 years)...
http://www.tobogganasbl.be/activites/?sector=LG