I am a primary school teacher. There was absolutely NO way I could have done even a remotely decent job whilst I was on chemo.
There is the viewpoint that not only will you be protecting yourself by staying away (if you can financially) the kids will not have to have multiple support people stepping in when you require some days off - here and there and I think it is highly likely that you would not be able to work every day or give it the energy it requires. Working with kids is exhausting in a variety of ways.
My advice is to do yourself a favour and step away for this period of time.
You can then bounce back and be there when you can give it your best and the dedication and energy it requires.