Talk about alternate character interpretation!
I like the concept you got going~ The writing is alright, but if there're some things that could use a bit more work, it's some of the tweening and the voice acting (especially the sound quality).
For the tweening, at times it's stiff or "unclean". Like where the arms connect to the shoulders or the forearms connect at the elbow, they sometimes look like disjointed rectangles/shapes with not enough room to actually be attached at the intended point. It's most glaringly obvious when you can see between the end edges of the shapes and when the lines don't connect. A trick a lot of tweening animators use is have something "extra" going on at the pivoting point (like a big rounded knob), so when an arm or leg bends, the edges of a square or rectangle isn't seen.
For the voice acting, I have to say, for people who don't seem to voice act too often, it's passable. Muted and often flat, but it works for a bunch of teachers sitting around to talking to each other. It's when voices are raised that sound quality becomes an issue and a possible reason why the performances seemed held back--Peaking! Oh gawd, when Ms. Frizzle showed up and started talking loud, it hurt my ears because of the mic distortion! The energy is appropriate and I wish she was even more crazy (imagine that), but the volume? Ouch---It's like having my ears screamed into!
I don't know what program you're using to record, but if it's Audacity, its volume control sucks. Trust me, I used it for years and it always failed me when I needed to scream. Wavepad has only 1 editing track, but at least you can change the volume of a clip through its amplification feature and if you're crazy ghetto, you can record things one by one in Wavepad and attach everything in Audacity. As for the mic issues going on, lower the gain of the mic and/or back up from it while screaming. Not sure if you're using Windows or a Mac, but there should be a way to adjust the input volume in the sound settings somewhere.
I hope what I had to say will help you for the rest of the series!