Powell has been diagnosed with ADHD and is listed on the UK Special Education Needs Register.
His dad Damian Lightoller, told The Observer that he was stunned when his son told him about the poster he was forced to make after asking for help with the bullies.
According to Lightoller, his son tried to ask for help in a situation that was causing him extreme stress but was let down by his teacher.
"My son sought help from a teacher, and rather than discipline the other children for bullying, (the mentor) blamed the victim and said, 'Well, you need to not do this, this, this and this'," he said.
After complaining to the school, a "furious, upset and hurt" Lightoller claimed the school's principal described the session as "restorative justice".