At Planet Schule, you'll find films, educational games, simulations and apps for every subject.
The site is in German and contains materials on pretty much every topic you might ever learn at school. From volcanos to insects, from energy production to the middle ages.
Each resource is also available as a free download.
If you share your computer, laptop or tablet with your siblings or parents, then you can also learn via the oldschool method of the television because WDR are broadcasting Planet Schule every day from 7:20 to 8:20, and SWR are broadcasting from 10:45 to 11:15.
More information here: https://www.planet-schule.de/