Maybe you could go to your work like this? Except with pants that fit right.
But it's a blazer which gives you some professionalism with a henley that doesn't make it too formal for a teaching man. Pants just get something basic that fits I'd go black. Shoes are sweet. Most importantly it's pretty safe so the kids won't have anything to make fun of.
Don't go dressed to work/school like that.
You'll get shredded for wearing a blazer with a henley (too hip/and some insults I won't repeat here etc).
From experience, the teachers that classmates didn't ever tear apart were the ones who wore suits that weren't associated with geography or latin teachers (i.e. ill fitting dull/old tweeds and corduroys).
Looking back, one teacher used to wear an exceptionally well cut suit, which we obviously didn't know back then, we just thought he was not to be messed with. His clothes were never mentioned.
Any teacher that wore a blazer without a (proper) shirt appeared to us to be trying too hard/hip and was given no quarter. (Unfortunate, but that's how it went). An exception was made for a maths teacher who was considered a drunk, so his cowboy boots, slacks and henleys were admired....lol.