Its not particularly in order but image 2-3 show a male with red hair (teacher) and images 25-27 show some changes; 38 shows some sex with small boobs and if you look around more you'll see the gradual changes from the male red haired teacher to a female with red hair and large breasts. (yay for gender bender!)
Edit: I see, I only meant the 'transformation' order (like how 9-10 is much further along than 25) I haven't actually played the game. :S
@reyzal: believe it or not this is the order as they happened in game. The only difference is that the endings (69-87) are set aside. It's more that the story was all over the place and had the occasional masturbation flashback than anything else.