i think a prochem fivestar would be ideal , small and convienient and easy to use, prochem also provide the training needed and the chemicals.
they are also extremely pc on which chemicals are correct for use in schools as health and safety is paramount.
Dave
I would agree with this, I have 6 on the go and they are perfect for this kind of job.
Good performance, compact, tidy and easy to maintain. Just check vac cover for cracks and footplate for damage if buying used, they sometimes take a few bumps to the front and can get damaged after time.
Apart from that all good and can go for around £300 on ebay, bargain.