Dr Sansom's EXTREME facts

The first teabag

You shouldn't drink tea. It makes your teeth go brown.

Here in the Extreme Facts office we drink too much tea: sometimes up to 25 pints a day. Plus, we sometimes have half a gallon of coffee, a milk-float of milk, and all the water in the tap.

As a result, Dr Sansom himself has no teeth at all. And there is a whole load of washing up to do at the end of the day.

The first tea bag was invented in 1908, by Thomas Sullivan.

Sullivan put tea in tiny silk bags. People were supposed to cut the tiny silk bag open and put the tea in a pot. But they poured hot water on the bags instead. Eureka! The tea bag was born.

The last US president

You know all about Barack Obama, obviously. The 44th American president, and the first African American to hold the office.

(If you have a very important job you don't just do the job, you "hold the office". Do you hold any office? If so, email extreme.facts@guardian.co.uk).

American presidents are elected for four years. Then, if people vote for the person again, they can be president for another four years, but no longer than that.

The last president to serve more than eight years was Franklin D Roosevelt. He was president for more than 10 years, from 1933 to 1945. The American Congress then passed a law to stop it ever happening again.

The best inventor

Have you ever invented anything? Anything at all? A new sandwich filling? (Dr Sansom's favourite sandwich filling is peanut butter, Marmite, and mayonnaise. Delicious.)

One of the youngest inventors ever was Louis Braille, who came up with the raised-dot writing system for blind people.

But the greatest inventor in the world, ever?

There's no doubt. The best inventor in the world ever was Leonardo da Vinci. His inventions include the alarm clock, cranes, the diving suit, a flying machine, a helicopter and the parachute, although he didn't actually build all of these things. He drew them in a notebook.

Quick! Get out your notebook!

The worst invention

The worst invention in the world would be an invention that didn't work. If you invented a new kind of eco-toilet, for example, to save water, and it didn't flush away the poo.

That would not be a good invention.

The worst ever invention may be the parachute fire escape, which was invented by a man called Benjamin B Oppenheimer in 1879 (US Patent 221,855).

The parachute fire escape was a parachute you could wear on your head if you got stuck in a burning building and had to jump out
of the window. It included padded shoes to soften the landing. Ouch.

The smallest mammal

Are you small? Are you tiny? Are you a wee slip, a titch, a tot,a tiddler, or a mite?

There is absolutely nothing wrong with being small. Small is beautiful.

The shortest mammal by length is Kitti's hog-nosed bat, sometimes called the bumblebee bat, which is less than 3cm in length. It is called hog-nosed because it has a snout like a pig.

It is smaller than a pipistrelle bat (about 4cm), a little brown bat (about 4cm), and a southern blossom bat (about 5cm).

Basically, there a lot of very small bats.

The biggest species of mammal

Have you ever seen a guinea pig? Yes? Good. A squirrel? Yes? Have you ever eaten a porcupine? No? Oh well, never mind.

Squirrels and guinea pigs are rodents [ROW-DUNTS]. There are over 200 species [SPEE-SHEEZ] of rodent, making rodents the mammal with the largest number of species. A species is a group of creatures or plants
which have lots of things in common.

Species of mammal include primates (monkeys, apes, humans, etc) and marsupials (kangaroos, koalas, opossums).

But getting back to rodents, apart from squirrels and guinea pigs, can you think of any others?