I too work at a school - these dresses are great. I love my clothes from Athleta and Title Nine - they wash well and wear easy: they keep their shape and their color for wash after wash. I love them because i can wash them, hang them and they'll be DRY in the morning. Certain times of the month I have more body odor and the polyester can emphasize that- but i just carry my deodorant in my bag and it's all good. Cotton is great of course but too much trouble to iron, and it doesn't keep it's color. I wear cotton at home when i'm snuggling my kids.

OP i think you're on the right track. Love the shoes. Your students don't care what you are wearing - as long as you are on time and comfortable enough to pay attention to THEM. Good luck! Have fun!

PP here - I think the shoes are totally appropriate, especially since you are probably on your feet alot and given your description above.