What's the Difference Between Yams and Sweet Potatoes?

Julia_Sudnitskaya/iStock via Getty Images
Julia_Sudnitskaya/iStock via Getty Images

This Thanksgiving, families across the country will enjoy a traditional meal of turkey, stuffing, and sweet potatoes ... or are they yams? Discussions on the proper name for the orange starchy stuff on your table can get more heated than arguments about topping them with marshmallows. But there's an easy way to tell the difference between sweet potatoes and yams: If you picked up the tuber from a typical American grocery store, it's probably a sweet potato.

So what's a sweet potato?

Sweet potato and yam aren't just different names for the same thing: The two produce items belong to their own separate botanical categories. Sweet potatoes are members of the morning glory family. Regular potatoes like russets, meanwhile, are considered part of the nightshade family, which means that sweet potatoes aren't actually potatoes at all.

Almost all of the foods most Americans think of as yams are really sweet potatoes. The root vegetable typically has brown or reddish skin with a starchy inside that's orange (though it can also be white or purple). It's sold in most supermarkets in the country and used to make sweet potato fries, sweet potato pie, and the sweet potato casserole you have at Thanksgiving.

Then what's a yam?

Yams.
Yams.
bonchan/iStock via Getty Images

Yams are a different beast altogether. They are more closely related to lilies and grasses and mostly grow in tropical environments. The skin is more rough and bark-like than what you'd see on a sweet potato, and the inside is usually white or yellowish—not orange.

They're a common ingredient in parts of Asia, Africa, and the Caribbean. Because the inside of a yam is less moist than the inside of a sweet potato, they require more fat to make them soft and creamy. They're also less sweet than their orange-hued counterparts. In many regions in the U.S., yams aren't sold outside of international grocery stores.

Where did the mix-up come from?

Also sweet potatoes.
Also sweet potatoes.
Kateryna Bibro/iStock via Getty Images

So if yams and sweet potatoes are two totally different vegetables that don't look or taste that similar, why are their names used interchangeably in the U.S.? You can blame the food industry. For years, "firm" sweet potatoes, which have brown skin and whitish flesh, were the only sweet potatoes grown in the U.S. In the early 20th century, "soft" sweet potatoes, which have reddish skin and deep-orange flesh, entered the scene. Farmers needed a way to distinguish the two varieties, so soft sweet potatoes became yams.

Nearly a century later, the misnomer shows no signs of disappearing. Many American supermarkets still call their orange-fleshed sweet potatoes yams and their white-fleshed ones sweet potatoes, even though both items are sweet potatoes. But this isn't a strict rule, and stores often swap the names and make things even more confusing for shoppers. So the next time you're shopping for a recipe that calls for sweet potatoes, learn to identify them by sight rather than the name on the label.

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What Happens During a Jeopardy! Commercial Break?

Jeopardy! host Alex Trebek chats with the show's contestants.
Jeopardy! host Alex Trebek chats with the show's contestants.
Getty Images Entertainment

Jennifer Quail:

Typical Break One: First, if there are "pickups" (re-recordings where Alex misspoke or coughed or stuttered, or Johnny mispronounced someone’s name or hometown) to record, they do those. A stagehand brings water bottles for the contestants. The production team who wrangles contestants comes over and gives their pep talk, makes any corrections, like if someone is consistently buzzing early; and keeps you quiet if there are pickups. Alex gets the cards with the "fun facts" (there are about three, one highlighted, but which one he goes for is ultimately up to Alex alone) and when the crew is ready, they come back from commercial to Alex’s chat with the contestants.

Typical Break Two: If there are any pickups from the second half of the Jeopardy! round they do those, the water gets distributed, the production team reminds the contestants how Double Jeopardy! works and that there’s still lots of money out there to win, and Alex comes over to take a picture with the two challengers (the champion will have had their picture taken during their first match.) Then we come back to Double Jeopardy!.

Typical Third Break: This is the big one. There are pickups, water, etc. and they activate the section of the screen where you write your wager. One of the team members brings you a half-sheet of paper ... and you work out what you want to bet. One of your "wranglers" checks it, as does another production team member, to make sure it’s legible and when you’re sure that’s what you want, you lock it in. At that point you can’t change it. They take away the scratch paper and the part of the board where you write your answer is unlocked. Someone will tell you to write either WHO or WHAT in the upper left corner, so you do know at least whether it’s a person or thing. They make sure the "backup card" (a piece of card stock sitting on your podium) is turned to the correct who or what side, just in case your touchscreen fails. If everything’s ready, then as soon as the crew says, they come back and Final Jeopardy! starts.

There are breaks you don’t [even know about, too]. If there is a question about someone’s final answer, they will actually stop tape while the research team checks. Sometimes if something goes really off, like Alex completely misreads a category during the start of a round, they’ll stop and pick it up immediately. Those [are breaks] you’ll never notice because they’ll be completely edited out.

This post originally appeared on Quora. Click here to view.

Why Is There a Leap Day?

Bychykhin_Olexandr/iStock via Getty Images
Bychykhin_Olexandr/iStock via Getty Images

At some point in elementary school, your science teacher probably explained to you that there are 365 days in a year because that’s how long it takes for Earth to complete one full rotation around the sun. What they might not have specified, however, is that it’s not exactly 365 days—it’s actually closer to 365.2421 days.

So, if we want our calendar year to begin right when Earth begins a new rotation around the sun, we have to account for (roughly) an extra quarter of a day each year, or one day every four years. History.com reports that the Egyptians had already been doing this for a while before Europe finally caught on in 46 B.C.E., when Roman dictator Julius Caesar and astronomer Sosigenes put their heads together to come up with what we now call the Julian calendar, which includes 12 months, 365 days, and an additional “leap day” every four years on February 29.

But rounding 0.2421 up to 0.25 each year created an issue, because it didn’t quite add up to a full day every four years—and that tiny discrepancy meant that after 128 years, the calendar year ended up starting a day before Earth had completed its rotation around the sun. By the 14th century, the calendar year was starting a whopping 10 days before Earth finished its orbit.

In 1582, Pope Gregory XIII sought to correct the error by suggesting that we simply skip a leap day every so often. His Gregorian calendar, which we still use today, mandates that we omit the leap day during years evenly divisible by 100 but not by 400. For instance, the year 2000 included a leap day because it’s divisible by 100 and 400; the year 2100, on the other hand, will not include a leap day, since it’s evenly divisible by 100, but not by 400.

Gregory XIII’s correction to Caesar’s overcorrection is itself a bit of an under-correction, so we’ll probably need to reevaluate our leap day protocol again in about 10,000 years.

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