After looking at the net frog simulation, I am not too sure about the usefulness of this tool to help students practise before a dissection. It is quite easy to follow, and seems easy when you look at it on the screen, but it might not be so easy to do when you have the actual frog in front of you. As I never got to dissect a frog during my biology lessons (or a heart), I dont know how easy or difficult it is to do so. I believe the simulation should be more interactive, letting you do the disection yourself, for example, or having some "Frequent Problems" site, as we assume not all frog are exactly the same. Furthermore, I think it is cruel to kill a frog just to see how its organs are, if you are not going to eat it later on.