I find this extremely interesting since we have 10 year olds using Git and GitHub with little difficulty, including from the command line. We do have to create the ssh keys and add them by hand for each student initially, but once setup students use a command-line
[ ! -z "$*" ] && comment="$*"
git add -A .
git commit -a -m "$comment"
We've actually had more success from the command line using this than using the desktop github tool.
I have seen material from FreeCodeCamp.com about GitHub and Codecademy.com also has a GIT tutorial. But you may be running into other aptitude issues with this group of students sounds like.