The one ruler that I find indispensible is the good old 6-1/2" square - I use it probably more than any other. But the 6x24 is also a great size to have. If you think you will love quilting (which of course you will) go ahead and buy a few basic supplies, but you will definitely add more as time goes by. Rotary cutter, cutting mat, a couple of rulers, scissors, pins, and don't forget the essential seam ripper (we all have to unsew at times)... Have fun at your class and hopefully you will be totally hooked on quilting!!