Crystal was introducing to students the topic of the menstrual cycle, as part of the larger theme of sexual reproduction in humans.
She decided to pose to them an overarching question on KF (Fig. 1): "Instead of menstruating every month, why is the uterine lining (endometrium) not sustained continuously throughout the life of a woman from puberty to menopause?" She provided students with readings as well as some guiding questions to stimulate their thinking, e.g., Why is there a need for the menstrual cycle? What is the uterine lining used for?
Consequently, due to time constraints, Crystal explained to students the four theories put forth by the readings she provided to them. She instructed them to choose and explain which theory out of the four, in their opinion, best answers the overarching inquiry question, and to explain the reason(s) behind their choice.