I too really recommend the soft frisbee as shown above. I have seen dogs lose teeth with the hard frisbee, however if you will be competing in any contests they won't let you use the soft ones. Our little Nina has become pretty good at it. I actually started her with one of those little soft ones, about 6 or 7 inches diameter. We would throw it for her in the house and all of a sudden one day she started catching it. I then got her the bigger soft one and threw it a short distance, gradually further.
A friend of mine has a blue heeler that is really good at it, he can't do the hard ones because they cut his mouth and he is a hemophiliac, the bleeding won't stop, so he is the one that got me into the soft ones. Our two run out together for the frisbee, the heeler(Bo) is such a gentleman he lets our little Nina catch it half the time, even though Bo is much better at it. Today Nina tipped one and Bo leaped into the air and caught it. It was spectacular!!! Anyway, if you see bleeding I'd go to the soft one, and check the teeth too.......tom