What would one suggest for remote teaching software for Ubuntu? I mean, if I would like to teach someone for example Python programming, pupil would see what I'm doing on my computer and hear my voice.
I would recommend using zoom.us. Zoom is a video conferencing solution like Hangouts and various others. The difference is that it has a native app for Ubuntu and other distributions.
On the settings page, you'll want to enable Join from your browser link. This way the recipient does not have to download the app. However, they may have a better experience if they also download and install zoom on their computer.