11 surprising ‘facts’ you were taught at school which are no longer true, including the power of carrots

It’s funny how time can put a new perspective on things.

Traditions change as the years roll by as does social etiquette, morals - and ‘scientific facts’.

You may be surprised to discover that some theories we were taught about the world around us in the classrooms of years gone by are no longer true.

Here’s 11 ‘facts’ you were probably taught at school which were either never true in the first place or are no longer correct.

1) Pluto is a planet

If you went to school before 2006 you probably learned there were nine planets in our solar system. It was technically correct at the time, until Pluto was downgraded that year to a dwarf planet. 

It's one of five dwarf planets, along with Ceres, Haumea,  Makemake and Eris. Pluto's demotion was a particular problem if, like me, you learned to remember the planets and their order using the handy mnemonic 'My Very Easy Method Just Sets Up Nine Planets'.

2) Chameleons can blend into any background

Most people grew up thinking chameleons could change their colour to camouflage themselves against any background, but it turns out this is not entirely true. According to the National Geographic, while chameleons can make small adjustments to their hue to blend into their surroundings, the most dramatic colour changes come when they're defending their territory or putting on a display to attract a mate. Chameleons do blend into their background without changing colour as in their normal state they resemble the leaves and branches found in their natural habitat. This is lucky since they lack any defence mechanisms, like a powerful bite, poisonous skin or fast movement. To be fair, teachers aren't the only ones to blame for this common misconception about the extent of chameleons' colour-changing - Disney's Tangled, and its loveable chameleon Pascal, also has a lot to answer for.

3) The Great Wall of China is visible from space

The Great Wall of China is a remarkable feat of human achievement, but the romantic notion that it is the only man-made structure visible from space simply isn't true - even if you did learn it at school. While the wall is incredibly long it's actually quite narrow, making it impossible to spot from space with the naked eye. There are some man-made structures which can be seen from space, however. The astronaut, Leroy Chiao claimed to have seen two of the pyramids while looking down at Earth, and NASA says the Three Gorges Dam in China can be seen from space.

4) Carrots can give you night vision

The idea that eating enough carrots will make you see in the dark is one peddled by many parents desperate to get their children to eat more vegetables - and something some people remember being taught at school too. The myth reportedly has its roots in wartime propaganda. The British government circulated the claim that its fighter pilots were so good at shooting down German planes at night because they ate so many carrots, when in fact it was down to the use of radar, which they wanted to keep secret. Eating carrots does have some benefits for your eyesight, however, as they are a good source of beta-carotene which is converted by your body into retinol, which is vital for healthy eyes.

5) You have taste zones on your tongue

We all remember the diagram in biology lessons showing the different zones on your tongue, which could supposedly register sweet, salty, sour and bitter tastes. While some parts of the tongue are more sensitive than others, there are not specific areas which are better at identifying certain tastes. This widely taught myth is understood to have stemmed from the misinterpretation of a 1901 dissertation. As well as being able to sense sweet, salty, sour and bitter, each taste bud on our tongue can also identify umami, which was only recognised as the fifth basic taste in 1990.

6) I before e, except after c

This spelling mantra trips off the tongue and was taught to generations of schoolchildren, but in the late noughties the government decided it was no longer worth teaching as there were simply too many exceptions, like neighbour, height, weird and science.

7) There are only three states of matter

Many 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'.

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.

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.

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.

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.