Teacher A was useless told DD1 to stop fussing, your always loosing things.
Teacher B believed her, found her two lunch bags in places they were clearly hidden, kept an eye on the culprits.
Teacher B did a pretty good job of reducing these two boys antics for the next two years and of reining in some of the girls without pointing out it was mainly on DD1's behalf.
(DD1 is dyslexic and the sort of quirky slightly socially inept child who will get bullied. The worst culprit for bullying her simply wasn't taught its not big or clever to bully at home. His main carer seemed to think picking on DD for being different was perfectly acceptable 
)
Senior school have always found DD someone to talk to if she gets a hard time and the odd detention has been doled out. Also they don't force DC out side at break, so DD1 was able to stay in the library and read and has ended up as a librarian.
She is now in Y10 and says the worst nastiness tapered off in Y9. She has grown up, a lot, she is way less easy to fluster and not as load. They have realised that they aren't going to get a reaction. Also DD1 has brains and sometimes she is actually useful to be nice to.
Most of all DD1 has a deep calm self confidence, she knows she pretty bright and she is a very good singer, which earns a certain amount of grudging respect.