Continuing Nick's thought - plastic juice pitchers from Target should work just fine. If you are setting up a teaching darkroom, it's likely that you will want to establish some "house standards" in terms of developers, dilutions, etc. In that case, you could use a master graduate to measure quantities of plan water, transfer that water to your teaching graduates, and then mark them with a Sharpie.
In my home darkroom, I have a plastic graduate with two green marks representing the volumes of HC110 stock solution required for one or two rolls, respectively, of film. I've long since forgotten how many ml of the stock is required - I just fill the graduate up to the green line, and add water to make the volume required for the tank that I will be using.
Another thought - when I first set up my darkroom, I bought a 1 litre glass graduate that started life as measuring cup for kitchen applications. I've noticed that you can find these now in plastic.