I am concerned that none of my eggs hatched. I picked up 2 dozen for my class and 2 dozen for Mrs. O'Briens class. She had about a dozen hatch. We did all the same things. I have documented my turning times, temp., humidity, etc. The only difference I can think of is I used a circulated air incubator and she used a still air one. I let 2 of my students crack open an egg at the end of the day to investigate and they were both yellow yolk, one we noticed what looked like an eye, but nothing else in either? I am wondering what might have gone wrong in your opinion? Do you feel that I should have my kids open all of the eggs to investigate? Any suggestions? Thank you.