Thin canvas sheets that come in pads which are ready to use will work fine. However you can use canvas panels, pre-stretched already primed canvases, linen / cotton fabric canvas which is used to stretch your own canvases. All these types of canvas are sold at Creative Boost. Canvas fabric comes in linen and cotton; linen has a smoother feel and is nicer to use, but is more expensive. Both cotton and linen come unprimed and primed; primed means that the necessary undercoating of gesso has already been applied, and the canvas can be stretched over your wooden stretchers, and painted on right away. Unprimed means that you need to put two coats of gesso on the canvas. Canvas fabric comes in three weights – the middle weight usually works well for most users.
Supports other than canvas that can be used include masonite, wood panels, and heavier paper. These must also receive two coats of gesso priming before painting. Masonite (the smooth side) must also be sanded lightly before priming with gesso. For acrylic paints, you can also use any of the above support types, and the gesso priming would be done the same way as for oil paint.
Be prepared to have at least two different size supports per class. It is a good idea to try various types and sizes as to get accustomed to these.