An example of a grad-school level question?
In the morning, students observed puddles of water all over the playground. What would best explain why the playground was dry in the afternoon?

An example of a grad-school level question?
When a dog smells food and begins drooling, it is responding to an external stimulus. Which of these describes a response to an internal stimulus?

An example of a grad-school level question?
A negatively-charged ion has

An example of a grad-school level question?
NASA's Kepler Mission has collected information about main-sequence stars with characteristics similar to the Sun. What is the most common color of these stars?