Integrating major course ideas into coherent themes is a big deal for me. I introduced the topic here. One that I really enjoy is teaching biology with the flu virus (follow the link for resources associated with discussion below). Briefly, influenza attaches to the surface of your cells through specific interactions, is internalized, and then all hell breaks loose when you pump protons into the resulting vesicle. You’re trying to digest it. Its waiting for a sign it’s inside.