From Google: "Homeschooling has been illegal since 1919. In very exceptional cases, you can take your child out of the education system and school them at home. You need to prove that attending school would cause the child unnecessary hardship. Only around 400 students across Germany are home schooled."

Even if you skip a day without a reasonable note from your parents or doctor's sick note, parents may get fines for their child skipping school days. Now, though there is no mandatory vaccinations in Germany they "basic" ones are required by law for school. Thus parents are being forced into vaccinating their children. Not because of any illness but through the compulsory schooling law.