A good (reasonably not bad) example of the rheology of the mantle is Silly Putty.

If you put a ball of it on a desk and hit it with a hammer, it shatters. A good analogy for earthquakes (brittle response)

If you just leave it on the desk it will become nice flat putty pancake (ductile response)

Two different responses to two different stress/strain regimes. Particularly effective in class