Given that the little ones will have administrator privileges this method may be temporary.
Click on the Start orb and type in "device manager" then hit enter.
Scroll down to "Network Adapters" and expand by clicking on the little arrow on the left.
Look for your wireless adapter and right click, then click "disable".
Do the same to re-enable.
Kids are very computer savvy now days so this measure might be temporary but it is worth a shot.