An occasional column on developments in what educators call STEM — for science, technology, engineering and math.

Wake up, scientists. America’s 11-year-olds want you to explain sleep.

It has been more than two years since Alan Alda asked scientists around the world to answer the question “What is flame?” in terms that a sixth grader could appreciate. The contest, called the Flame Challenge, was inspired by his own curiosity about fire as an 11-year-old.

This year, the Flame Challenge tackles the question “What is sleep?” Scientists can submit answers in writing, graphics or a video to be judged by a panel of children.

“Sleep is something mysterious to all of us at every age,” Mr. Alda said in a telephone interview. “I think the idea that you get drowsy and drop off at a certain point is a weird experience, and it happens to everybody. So what is it? Why do we do it?”