BandLab is a free service that enables you to create music in your web browser or through free Android and iOS apps. In BandLab's you can create soundtracks using any of the virtual instruments that are provided. You can also speak or sing to record a track. Within the BandLab editor you can mix your tracks together to create a song. If you have existing audio files on your computer, you can upload those to incorporate into your BandLab creations.
BandLab is designed to allow you to collaborate with others. To collaborate you first have to create a band in your BandLab profile then invite other users to join your band.
Applications for Education
BandLab offers one way for high school students to collaborate to create music. That music could then be downloaded and used in other places like as background music in a video. BandLab could also be used to create simple podcasts.
One aspect of BandLab that teachers should be aware of is the public profiles that can be followed in the BandLab community. Those profiles feature the creations of other users. It doesn't appear that those creations are moderated for language.