King Kong’s original bellow was supposedly a mix of tiger growl and lion roar played backwards at half speed, the Rancor in Return of the Jedi was a slowed-down chihuahua, and Chewbacca was a stew of badger, bear, and walrus.
Mix together at least THREE sounds (at least one animal and one inanimate/inorganic object), altering at least one (i.e. slowing it down, speeding it up, playing it backwards) to create the shriek/roar/yawp or indecipherable language of a made-up monster/species. Decide what your monster/creature looks like and try to evoke a specific picture with your final sound. Can the listener tell what your creature looks like by the noise it makes? That's the goal.
Attach your recording to a black frame and post it in the Comments section of the relevant entry on the class's FB Group page, Billy Lich & His Bucket List. (But find, too, an image that matches the sound; have it ready, but don't reveal it until the class guesses).