It could start with something as simple as a basic dress...
the dress should be half way down the calf with darts to make it more flattering for all figures. The sleeves would be long but can be pushed up.
The fabric should be sturdy, in case the teacher rubs against a rough surface that could snag more delicate fabric. The fabric would also be stain resistant since teaching is a messy profession, quick to dry, and sturdy to survive many times through the washing machine. The shirt should be of a fabric that does not suffer with static cling or wrinkle. The fabric should also have some lycra or other stretchy fabric as a component to make it a more comfortable fit.
The dress would be reversible with a strong print on one side and a solid neutral color on the other.
Step 1: Storage Within the Garment
they need to have pens and pencils, so a pocket for this that is lined so that if the pen leaks it does not ruin the dress would be a necessity. This is the upper arm pocket which should be an invisible pocket just wide enough for about three pens.
there is often not somewhere convenient to stash a wallet and cell phone so the pockets at the waist (which should be accessible from both sides since the dress is reversible) should be large enough for a cell phone on one side and a wallet on the other.
The two bottom pockets would be open by slits in the center that would close with velcro panels for storing extra blank hall passes, stickers to put on student papers when they do good work, and other odds and ends of teaching.
Step 2: Fashion Accessories
The belts would be long scarves causally tied at the waist with instructions for tieing it in several different methods for a variety of looks.