When McDonald’s came to the Soviet Union in 1990, the company insisted that workers smile. That didn’t come easy. But customers grew to like it — and workers did, too. What happens when you change a norm?

Editors’ note: We’re launching the second season of the NPR podcast Invisibilia by exploring norms — how they shape our lives, often without us realizing it, and what happens if we change them on purpose. On Morning Edition, Alix Spiegel finds out what happened when McDonald’s told employees in the Soviet Union that they had to smile. Our health blog, Shots, looks into an oil company tried to prevent injuries and deaths on offshore rigs by asking roughnecks to talk about feelings. You can read that story below.

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