A trick I have used with my kindergarteners was to seat them alphabetically
by first names -- if I looked at a particular table I knew their name began
with A or something close. So I knew William couldn't possibly be that
kid's name! I explained why I was doing it too so they helped me out.
Takes me about half a year to get to know all the new Kdg kids (about 120 of
them). I imagine it would work with older kids as well.
Liz in rural NY