Reading Glasses

So – my eye doctor warned me a few years ago and it is happening…. I need reading glasses. Since I’ll be starting class in a couple weeks – I want to order some glasses that I’ll be able to leave on during class (I only need them for reading – can’t actually see distance with them on). I am looking for glasses that have a reading lens on the bottom but are clear on top so I can see the board. Does anyone know if these exist or what they would be called? Everything I have found so far is has some sort of magnification all the way up (like 3/4 for the center and 1/2 for the top – but not totally clear).