Unfortunately, Go Animate for Schools is shutting down...
Alternately, try; Animatron - lots of premade scenes and animations - easy to make and can voice record straight into the video - able to download as mp4 or gif
Other alternatives..
Biteable - very basic simple to make an animation, use images and animation and add text, cannot voice record but can upload pre-recorded audio. Cannot download, but can share link/embed
Animaker - a pretty slow site, but easy to use.
Powtoons - fairly easy to use, but you need to make sure you only use the free (not pro) images/animations etc, otherwise it will have giant watermarks over the screen. Need to export to YouTube to share.
Also, there are also a bunch of iPad apps that you could use if interested - and there are 20 ipads in the library that you could borrow.