The Vikings discovered North America 500 years before Columbus.
Why it is true
Leif Erikson landed in modern-day Canada around 1000 AD at a site called L'Anse aux Meadows, long before Columbus arrived in the Caribbean in 1492.
Source: History
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.