ADHD stands for Attention Deficit Hyperactivity Disorder. It is characterised by the following:

Inattention e.g.
Works poorly without one to one supervision.
Flits from task to task.
Day dreams.
Forgets instructions.

Impusivity e.g.
Speaks and acts without thinking.
Interrupts.
Calls out in class.
Rushes through work.
Acts the clown

Hyperactivity e.g.
Restless.
Fidgety.
Taps, fiddles, touches.
Always on the go.
Takes risks.