I would try to maybe take 5 minutes of a class to focus on phonics. Try learning 1-3 different phonics 'rules' each class. Also, just not the b,c,d, etc. sounds but the more complicated ones like blends (bl, gr, nd, etc.) or pairs (a-e, ea, ie, etc.). Then, try to do a little game with that new sound(s), or after they learn a few, they can play a game with them.