Edumacation
I liked the concept. Not much educational stuff on NG. I feel like I learned a bit from it.
My only suggestion is to use the "streaming" sound setting in flash. It synchs your audio to your timeline so the audio matches perfectly with what's on the screen. (It will actually skip animation frames to maintain synch).
I could just tell you split up your audio into different segments to try to keep it synched well (I know cuz I did the same thing in my first flash anims). Streaming will even work with your scene selection system.
If you're worried about quality of sound, you can adjust the quality under file>publish settings in flash and up the bitrate till it sounds good.
Overall I liked it...keep up the good work!