Just in time for Spring, ScienceGoddess, aka Joanne Manaster, explains the cellular reactions that cause allergies. Her illustrations: candy (looks like Skittles or M&Ms) and a lovely cookie basophil made by food blogger Notsohumblepie. This video ends on something of a cliffhanger, so if you want to watch the next one, it's all about eosinophils.
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.