Now here is where things start to get confusing. The classroom is also a place you can put your Chao if you need to get them out of the Garden for a while (which helps to prevent unwanted aging). During some Chao races the intelligence factor of your Chao will play an important role in how well they do so try to keep them as intelligent as possible. The classroom is where your Chao improves its intelligence. Make sure you take some time before evolving it to send your Chao to class.
The Chao will throw the food away if they don’t want it. Your Chao will also eat these on their own so be careful not to over-feed them. Start by feeding it fruit from the tree in whichever zone your Chao is in. Once your Chao has hatched you can begin feeding it. I haven’t found any way to get a consistent face yet though.
Each one of these egg-hatching methods will give your Chao a different facial expression: mad, sad, or happy, or just a regular Chao. It will also result in your Chao not liking you right off the bat, so just don’t do it! Another method of speeding up the hatching process is to pick the egg up and jump around with it for a while before setting it back down. You can also throw it against the wall, although this will usually result in your Chao hatching with a pretty hideous expression on its face (and it’s permanent) so I don’t recommend it. You can let these eggs sit there until they hatch or you can pick them up and shake them to speed up the process (walk up to an egg, press and hold B and begin to move the control stick, much like how you shake down fruits from the trees for a few seconds and set it back down). You’ll start off with two Chao eggs when you first enter the Chao world. Most other guides merely list off a bunch of Chao evolution combinations and a list of colors well here is how Chaos really work…
Having troubles raising a Chao? After having searched around for information on raising and evolving Chaos I found information on them to be either scarce or non-existent.