An example of a grad-school level question?
When you are riding a bicycle at night, your bicycle's reflectors help people in cars see your bicycle. How do bicycle reflectors work?

An example of a grad-school level question?
Which is a way the agricultural biotechnology industry could have a positive impact on the environment?

An example of a grad-school level question?
Which two processes could result in the formation of high mountains with well-rounded peaks?

An example of a grad-school level question?
Scientists study the current conditions of many solar system objects to gain insight into conditions early in the history of Earth. Which phenomenon most closely models current theories of early Earth?