I would say so, yes. This looks like convenience sampling to me. The common factor amongst different types of probability sampling is random sampling (e.g. simple random sampling from a specific population, random sampling from within specific sub-populations in stratified sampling, etc.) There is no random sampling here - you've picked out schools presumably on a non-random basis, and even though you don't know exactly who will be surveyed, teachers will still hand out surveys on a non-random basis.