Disclaimer: I am not being reimbursed to spread my joy about these cups... I just really really love them. They come from Bando and they are really THE PERFECT CLASSROOM cup. They do not drip condensation all over my desk and papers. Ice stays cold for hours. They aren't glass, and are heavy duty. The downside is that I can't throw them into the dishwasher, but that's not the end of the world. I usually just fill the big cups up with ice and a slice of lemon at home, and haul them to school where I add water to get everything nice and chilly, then just continue to add more water throughout the day... I do use them at home too. :)
Have you shopped at Bando? It's an addicting little shop!