Animation and Simulation provide great oppurtunities for students learning where the real thing is not feasible. The ability to disect a frog creates a opportunity for students to learn about anatomy and body parts with out actually disecting a real animal. This is great as some students may find it sickening to do that to a real animal.
The ability to build an electrical curcuit online is a good tool when learning about electrical currents and power. This may be a cheaper option then buying all the parts to create one in class, althought may not be as beneficial as the hands on experience. As they do not learn what happens if you come in contact with the current, which is an important lesson to learn.
There are many other animation and simulation sites out with similar activities, i feel these tols would really enhance learning. While the task is not real as such it still provides real concepts and can feel very real for the students as it did for me. Chen (2002) believes "Computer-based simulations have the potential to enhance the transfer of learning by providing students with surrogate learning environments".
Here are some sites I found which have simulations check them out.
Chen, T. (2002). Design Considerations for Computer-based Simulations in Education. 16th Augast 2002. Retrieved from http://www.editlib.org/p/10144