spy camera needed to protect kids on bus

Our sons (8 and 11) are being verbally abused by their school bus driver. We’ve alerted authorities and submitted complaints and everyone seems to be protecting the driver and taking her side in what amounts to a he said / she said situation.

We need to rebalance the scales here. I’d like my older son to wear or have on him a camera that records his ride home in its entirety (about 30 minutes). It needs to record video and audio, and then easily dump the video to my Mac, but most importantly, it needs to be discreet.

Can anyone recommend a camera for this sort of situation? Looking online, there are heaps of hidden cameras available but not a lot of clear info on which is worth investing in, especially if you’re asking an 11 year old to operate it on the down low.