Function of Behaviour
The purpose a behaviour serves for the person — what it reliably gets them or gets them out of. The four commonly assessed functions are attention, escape, access to tangibles, and sensory/automatic.
Every repeated behaviour persists because it works. The function of a behaviour is what it reliably produces for the person: social attention, escape from demands or situations, access to preferred items or activities, or sensory/automatic reinforcement that does not depend on other people at all.
Function matters because the same behaviour can serve different purposes in different students — and the right response depends entirely on which one. Sending a student out of class is a consequence for attention-maintained behaviour and a reward for escape-maintained behaviour. Identifying function through ABC data and functional assessment is what separates a plan that works from a plan that accidentally feeds the problem.