Sophie conducts an experiment in which she creates a snot-like substance. She then explains the purpose of snot and provides a fun fact: we have mucus in our eyes.

Beakmans explains that onions make you cry because of the chemical that gets into your nose. He then uses a schematic of a bathroom drainage system as a metaphor for how your nose, mouth and eyes are all connected. Lester sneezes when his nose was tickled and this causes his eyes to shut because the muscles are connected.

The Eds are trying to sell ice cream to the other kids in the cul-de-sac, but no one appears to be around. They ring Jimmy's doorbell to see if he is home, and they are surprised to see that he has chicken pox. The Eds notice quarantine signs in front of everyone's house, meaning that they are the only ones who did not fall victim to the disease.

What is cancer, and how does it start? Find out how genetics play a role, which types of cancer are the most prevalent, and what is being done to fight this deadly disease.

This clip shows the different biosafety levels of a research facility. For each level, it lists the types of microorganisms that exist along with some of the viruses they could cause. It also shows the equipment and safety precautions used by the researchers at each level.