I think I see the problem. You apparently think that Fish ID is about looking at pictures. Actually, it's not. You may have noticed that in the pictures, all the fish are about the same size? And the pictures don't hide so all you can see are their eyes or their tail. And the pictures don't swim away. In fact, the pictures don't swim at all, so one of the best clues is not present. In real life, the class is about how to even find the fish, what is their behavior and habitat as an ID clue, and even time of day. and depth. You can ID all the pictures you want, and do an inept and terrible job on a dive. Looking at pictures is a start, just like looking at a video of someone in sidemount, but getting the rigging and trim right is an in-water skill....like Fish ID.
Sort of...if you are deaf. Ever noticed how many birders hear and ID the bird before they see it? Try tht underwater. Even if you hear the grunt of a ...well, grunt....you don't know where to look, becasue your hearing is not directional underwater. Think a good birder can learn how to do it from pictures of birds in a book? Nah.