For this project kids were first given Sharpies and paper the same size as their tiles. They used Sharpie to write their name on the back of their tiles, then they drew their design on paper first for practice. Then kids painted their designs onto the tiles. We used Enamels and Porcelaine brand paint for ceramic and glass. (Not sure if this is allowed in a school classroom b/c of safety restrictions - I did this lesson in one of my home art classes.)
Tiles were air dried 24 hours, then baked for 30 min. at 325 degrees. The oven does not have to be pre-heated, the slow temp. rise is helpful for no cracks. (Note, there is a chemical smell when baking, yuk!)