But 10 year olds know this too. I was a Den Leader for my son's Cub Scout den and a Girl Scout leader for my daughter's Girl Scout troop. I started teaching both groups about knives when they were 9 years old. They definitely knew not to take a knife to school.

Now, on the other hand, I can easily imagine one accidently leaving a folding knife in a backpack - after a weekend outing. I encourage my troops to use separate packs for Scouts and school to avoid that happening.