Series 4

The Lost Producer

Why do some people have a terrible sense of direction?

• 18 mins

Series 5

The Broken Stool

How much does the bacteria inside my body weigh?

• 17 mins

Series 5

The World That Turns

'Why does the Earth spin?' asks Joe Wills from Accra in Ghana.

• 15 mins

Series 5

A Code in Blood

Why do we have different blood types? Drs Rutherford and Fry investigate.

• 11 mins

Series 5

The Astronomical Balloon

'How far up can a helium balloon go? Could it go out to space?' asks Juliet Gok, aged 9.

• 15 mins

Series 5

The Forgetful Child

Why don't we remember the first few years of our lives?

• 16 mins

Series 6

The Cat Who Came Back

How do cats find their way back to their old home when they move house?

• 19 mins

Series 6

The Burning Question

What is fire? Is it a solid, liquid or a gas? Adam Rutherford and Hannah Fry investigate.

• 18 mins

Series 6

The Dark Star

The science sleuths investigate the question 'What's inside a black hole?'.

• 23 mins

Series 6

Itchy and Scratchy

Why do we itch and should we scratch?

• 21 mins

Series 6

Kate Bush's Sonic Weapon

Can sound kill? Inspired by a Kate Bush song, we ask whether sonic weapons could work.

• 21 mins

Series 7

The Curious Cake-Off

How to make the perfect sponge using the power of science.

• 19 mins

Series 7

The Polar Opposite

What would happen if the Earth's magnetic poles flipped?

• 19 mins

Series 7

The Sticky Song

Why do tunes get stuck in our heads? And what makes some songs stickier than others?

• 24 mins

Series 7

The Shocking Surprise

Why do we get static shocks? Our science sleuths try to crack another case.

• 28 mins

Series 7

Adventures in Dreamland

Why do we dream? Drs Rutherford and Fry delve into the science of sleep.

• 24 mins

Series 8

The Baffled Bat

How do bats echolocate? And why don't they get confused by neighbouring signals?

• 25 mins

Series 8

The Dreadful Vegetable

Why don't children like vegetables?

• 30 mins

Series 8

The Cosmic Speed Limit

Can anything travel faster than the speed of light? Drs Rutherford and Fry investigate.

• 22 mins

Series 8

The Curious Face Off

Are machines better than humans at identifying faces?

• 25 mins

Series 8

Goldfinger's Moon Laser

Could we shoot a laser to the moon?

• 24 mins

Series 9

The Enigma of Sex, Part 1

Why does sex exist? And why aren't we all the same sex?

• 24 mins

Series 9

The Enigma of Sex, Part 2

Why don't we have more than two sexes?

• 22 mins

Series 9

The Tiniest Dinosaur

Which is the tiniest dinosaur?

• 29 mins

Series 9

The Atomic Blade

What makes things sharp?

• 23 mins

Series 9

The Cosmic Egg

How do we measure the age of the universe?

• 30 mins

Series 10

The Fifth Dimension

Is there a fifth dimension? Hannah and Adam visit CERN to find out.

• 27 mins

Series 10

The Human Instrument

Why do our voices change as we get older?

• 27 mins

Series 10

The Déjà Vu

Why do we get déjà vu?

• 25 mins

Series 10

The Lucky Number

How do I win the lottery?

• 25 mins