We start off believing everything our parents tell us is true, then we think we know everything, and finally we believe everything we learn at school.
But it turns out that much of what you learnt at school, and have probably been telling your own children, is actually wrong.
The teachers aren’t always to blame. They’re often just passing on what was accepted wisdom back then, or in some cases teaching us things which were actually true at the time but are no longer.
Below are 11 ‘facts’ you were probably taught at school which were either never true in the first place or are no longer correct.
How many of these do you remember being taught at school and are there any others which you remember learning before finding out years later that they are wrong?
Do you have retro pictures or nostalgic memories to share with us? Send them online via YourWorld at www.yourworld.net/submit. It's free to use and, once checked, your story or picture will appear on our website and, space allowing, in our newspapers.
7. There are only three states of matter
Most of us remember being taught at school how matter can only exist in three states - solid, liquid or gas. But there are now believed to be five states, including plasma, which is found in lightning and neon bulbs, and Bose-Einstein Condensates (BECs), which NASA says are 'formed when particles are cooled to near absolute zero, causing them to coalesce into a single quantum object that acts as a wave in a relatively large packet'. | HERBERT NEUBAUER/APA/AFP via Getty Images Photo: HERBERT NEUBAUER/APA/AFP via Getty Images
8. Mount Everest is the world's tallest mountain
This is one pub quiz fact everybody surely knows, but it's only partially true. Measured by height above sea level, Everest is indeed the world's tallest mountain, soaring 8,849 metres. But if you measure from base to peak, the tallest mountain is Mauna Kea, a long-dormant volcano in Hawaii, USA, which is around 10,205m high, including the 6,000 or so metres below sea level. | Mailee Osten-Tan/Getty Images Photo: Mailee Osten-Tan/Getty Images
9. Diamond is the strongest substance on Earth
Diamonds are the hardest thing on Earth but not the strongest. According to Stanford Advanced Materials diamond is only the seventh strongest material known to man, with graphene - 100 times stronger than steel - topping the list. | STEPHANE DE SAKUTIN/AFP via Getty Images Photo: STEPHANE DE SAKUTIN/AFP via Getty Images
10. Your hair and fingernails keep growing after you die
Many people remember being taught this surprising 'fact' at school, but it turns out it's so surprising because it's not actually true. Once you die, the cell division which causes your nails and hair to grow stops. But your nails do appear to grow after death because the skin around them retracts as it dehydrates. In the same way, stubble can appear to be growing after death when it is in fact not. | George Rose/Getty Images Photo: George Rose/Getty Images
11. You can only fold a piece of paper seven times
Science teachers love telling pupils this and then challenging them to prove them wrong. The claim is true for an ordinary sheet of A4 paper, which quickly becomes too thick and small to fold any further. But the bigger and thinner the paper is, the easier it becomes to fold more times. The world record belongs to the California high school student Britney Gallivan, who in 2002 folded a 1.2km-long piece of tissue paper 12 times. | DON EMMERT/AFP via Getty Images Photo: DON EMMERT/AFP via Getty Images