If you haven't sat your 11-year old kid down to have that one on one talk (about piracy, not the birds and the bees) you probably should do that before you end up on the hook for thousands of dollars.
A German court has ruled that a father is liable for an audiobook his 11-year old son downloaded. The man told the kid to only use the computer for school purposes and not to simply download things. However, the court ruled that this was not a proper anti-piracy instruction.