A review of the SCT staging of “Elephant & Piggie’s ‘We are in a Play!’ ” It’s adapted by Mo Willems from his popular series of storybooks. It’s at the theater through Dec. 6.

Elephant is cautious and anxious; Piggie, carefree and optimistic. The two Mo Willems characters, heroes of a popular series of picture books, support each other in the kind of classic friendship ...