What are tariffs, how do they work, and what kinds of impacts might they have? Today's non-partisan coverage brings you multiple perspectives. Also featured: flooding in northwestern France and the history of two U.S. constitutional amendments. We're also examining how a medieval method of forecasting the weather eventually turned into a U.S. holiday -- and how (in)accurate its predictors can be.

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Today's episode was sponsored by EF Educational Tours. Win a trip for up to 10 students and go anywhere EF travels for FREE! Teachers, please go to eftours.com/worldatoz and enter by February 23rd.