Catch up TV
Series 1: 19. You Could Run at the Speed of Sound?
A fun run goes wrong when one ambitious runner tries running at the speed of sound.
Source: CBBC
Most recent episodes of Hey You What If?
Hey You What If?
Series 1: 6. You Could Levitate?
Good news - it’s possible to levitate! Bad news – there are some serious side effects.
15-05-2026
CBBC
Hey You What If?
Series 1: 5. You Could Go On Holiday To Mars?
Experience the ultimate in long-distance travel - a holiday on Mars!
14-05-2026
CBBC
Hey You What If?
Series 1: 4. You Could Turn Into A Giant?
Find out why turning into a huge giant would be no fairy tale.
13-05-2026
CBBC
Hey You What If?
Series 1: 3. You Could Take A Lift To Space?
What would happen if there really was a lift that took you all the way up to space?
12-05-2026
CBBC
Hey You What If?
Series 1: 2. You Could Dig Through The Earth?
The deepest hole humankind ever dug only got one thousandth of the way through the earth. But what would happen if you kept digging?
11-05-2026
CBBC
Hey You What If?
Series 1: 1. You Fell Into A Black Hole?
Experience the most extraordinary ride in the universe – falling into a black hole.
07-05-2026
CBBC
Hey You What If?
Series 2: 26. You Could Walk Up Walls
We take inspiration from the natural world as we imagine a new kind of superhero that can walk up walls.
06-05-2026
CBBC
Hey You What If?
Series 2: 25. Earth Ran Out Of Energy
We try out a crazy idea from science fiction to build a giant sphere around the sun and give us more energy than we'll ever need.
05-05-2026
CBBC
Hey You What If?
Series 2: 24. You Surfed Without Water
If the beach is too far to go but you still want to spend some time surfing waves, then why not surf on land instead? Well, there are some very good reasons people don’t s ...
01-05-2026
CBBC
Hey You What If?
Series 2: 23. You Were Indestructible
On the face of it, humans are a bit breakable. We have these hard skeletons that can crack if you have a tumble. But if we were indestructible, like a superhero, then we&rsquo ...
30-04-2026
CBBC
Most popular episodes of Hey You What If?
Hey You What If?
Series 1: 4. You Could Turn Into A Giant?
Find out why turning into a huge giant would be no fairy tale.
13-05-2026
CBBC
Hey You What If?
Series 1: 5. You Could Go On Holiday To Mars?
Experience the ultimate in long-distance travel - a holiday on Mars!
14-05-2026
CBBC
Hey You What If?
Series 2: 4. You Needed Two Of You
From cloning to 3D printing, what if we could actually make copies of ourselves?
13-03-2026
CBBC
Hey You What If?
Series 1: 6. You Could Levitate?
Good news - it’s possible to levitate! Bad news – there are some serious side effects.
15-05-2026
CBBC
Hey You What If?
Series 1: 3. You Could Take A Lift To Space?
What would happen if there really was a lift that took you all the way up to space?
12-05-2026
CBBC
Hey You What If?
Series 1: 21. You Woke Up As A Lizard Superhero?
Why waking up with lizard powers would make you useless on earth but a superhero in space!
02-03-2026
CBBC
Hey You What If?
Series 2: 23. You Were Indestructible
On the face of it, humans are a bit breakable. We have these hard skeletons that can crack if you have a tumble. But if we were indestructible, like a superhero, then we&rsquo ...
30-04-2026
CBBC
Hey You What If?
Series 2: 15. You Shrunk The Earth
We find out what would happen if you shrank the earth. You could jump higher and move faster, but you would end up with altitude sickness even at sea level.
20-04-2026
CBBC
Hey You What If?
Series 1: 26. You Could Fly Like A Bird?
Anyone can fly like a bird – you just have to travel across the solar system to do it!
09-03-2026
CBBC
Hey You What If?
Series 2: 11. Animals Were Supersized
We look at whether some animals can get gigantic and find out that if you are being chased by a giant snail or a humungous butterfly, then fear not, you must be dreaming.
24-03-2026
CBBC