Why do women have periods?

How menstruation works – Emma Bryce

How do pregnancy tests work? – Tien Nguyen

How in vitro fertilization (IVF) works – Nassim Assefi and Brian A. Levine

How do contraceptives work? – NWHunter

Why it’s so hard to cure HIV/AIDS – Janet Iwasa

How bees help plants have sex – Fernanda S. Valdovinos