Contact your nearest
Tiling Course provider and tell them TilersForums sent you. Keep in mind that really, they should make you sign something because ceramic broken tiles have VERY sharp edges, sharper than glass in some cases as the tiles the training centre's will use will often be of the cheaper ranges, which have thinner glazes on them, which means sharper sticky-outy bits when they're broken.
If your little ones cut their fingers, their mums could try sue the training centre up to a years or so after (might be more, might be less) and even the school could end up with hassle should a little one cut themselves.
The way to avoid that would be to ask for their off-cut and broken full-bodied tiles. Might not look as 'mosaicy' as ceramics can but they'll be much much safer for the kids and the school and even the training centre supplying you with them.
Sorry to be all health and safetyish about the matter. Just take it as speaking from experience on such a matter.
Thanks for registering by the way too.