Hitlergruß aka Hitler salute as a great fun for belgian pre-teen boys

On my way home in subway i saw approximately 11 years old boy with his twelve years old friend raising their hands to salute Hitler. They were accompanied with other schoolmates and teacher as well. I asked the lad if he is aware of what he is doing. He knew shit about the gesture, then I've asked their teacher if she knows what the lad was doing and she said : "Nothing, he was just raising hand." I've asked her if she heard about Adolf Hitler, and explained the elementary school teacher what this very raising of boy's hand means. Then I've exited the train on my stop, but fortunately meanwhile my let say monologue there was an lady who got involved with intention to explain the boys and the teacher what kind of danger Nazis were.