A load of tentacles
Humming a few Beatles refrains was the extent of his repertoire, but like the good teacher he is he got the class settled and organised with their set work and sat back.
"Please, sir, what's an octave?"
The heidie sized up his options and deployed thinking skills strategies.
"Right, what's an octagon?" The boy thought.
"OK, think about an octopus. What's it got?"
"Eight testicles," replied the lad.