Over time, even facts we consider steadfast truths can change.
People used to think doctors could forgo washing their hands before surgery. Knowledge is ever-evolving.
Other facts might have been taught incorrectly because the truth is more nuanced than grade-school students can understand.
The nine facts below probably changed since your school days, or were taught to you the wrong way.
THEN: America won its independence on July 4, 1776
NOW: America was not officially independent until seven years later, in 1783.
Every year on July 4th, Americans celebrate Independence Day with parades, barbecues, and fireworks.
But while the Declaration of Independence was adopted by 12 colonies on July 4, 1776 and signed by 13 colonies in August, America was not yet free from Great Britain's rule.
The American Revolution waged on for years. Finally, the Treaty of Paris was signed on September 3, 1783, and America became free.
THEN: George Washington's teeth were made of wood
NOW: Washington's teeth were human teeth from his slaves and also made from ivory.
A set of dentures that George Washington wore are kept at the Mount Vernon plantation house museum. The dentures are fashioned out of ivory and human teeth.
While historians note the "limitations of history" when sourcing Washington's human teeth back to the individuals they were taken from, written evidence shows Washington purchased teeth from slaves and made note of it in one of his ledgers.
Slaves during the 18th century sometimes sold their teeth to dentists to make money. In 1784, Washington "paid several unnamed 'Negroes' ... 122 shillings for nine teeth, slightly less than one-third the going rate advertised in the papers," according to PBS.
Washington likely then had the teeth implanted into his jaw in a surgical procedure common at the time.
THEN: Pluto is a planet
NOW: Pluto isn't a planet
We've known since the late 1800s that a ninth planet, after Uranus, potentially existed. In 1906, Percival Lowell, the founder of the Lowell Observatory in Flagstaff, Arizona, even began a research project intended to locate the mysterious "Planet X."