We jumped on an opportunity to rent an incubator and raise some chicks from eggs. We have done a whole unit on eggs and chickens.
Chicken eggs take 21 days to hatch. At day 6 we candled the eggs. We candled again at day 20 and removed two eggs that were obviously not fertile. On day 21 we started hearing cheeps from the incubator and saw tiny cracks in a couple of eggs. By the following evening, we had 11 healthy hatched chicks, and one that started hatching but didn't completely hatch.
Egg to chick by Millicent E. Selsam This is the most awesome book ever for this project. It shows the development of the chick at many stages. Be forewarned that is deals frankly with sexual reproduction.
The Chicken Book by Garth Williams
Chicks and Chickens by Gail Gibbons
An Extraordinary Egg by Leo Lionni