Catch up TV
Series 1: 1. You Fell Into a Black Hole?
Experience the most extraordinary ride in the universe – falling into a black hole.
Source: CBBC
Most recent episodes of Hey You What If?
Hey You What If?
Series 1: 25. You Could Switch Off The Sun?
See what would happen if you really could switch off the sun.
06-03-2026
CBBC
Hey You What If?
Series 1: 24. You Took All The Water Out Of The Sea?
Empty the oceans and you’d see hidden wonders, but you’d also cause the end of the world.
05-03-2026
CBBC
Hey You What If?
Series 1: 23. You Could Teleport?
Is it really possible to teleport? Spoiler alert: it could end in disaster!
04-03-2026
CBBC
Hey You What If?
Series 1: 22. You Could Build A Gingerbread House?
It’s the ultimate baking challenge: making a gingerbread house you could actually live in.
03-03-2026
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 1: 20. You Try To Catch A Falling Star?
What happens if you try to catch a falling star? Spoiler alert - probably best not to try!
27-02-2026
CBBC
Hey You What If?
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.
26-02-2026
CBBC
Hey You What If?
Series 1: 18. The Earth Was Shaped Like A Doughnut?
Would it be possible to live on an Earth shaped like a doughnut? You might be surprised!
25-02-2026
CBBC
Hey You What If?
Series 1: 17. You Could Live In Slow Motion?
Find out why living in slow motion would let you see things no-one else can!
24-02-2026
CBBC
Hey You What If?
Series 1: 16. You Could Actually Reach For The Stars?
Want to reach for the stars? It would be the journey of a lifetime - literally.
23-02-2026
CBBC
Most popular episodes of Hey You What If?
Hey You What If?
Series 1: 13. You Could Shrink Yourself?
If you have always wanted to shrink yourself, this is the episode for you!
11-02-2026
CBBC
Hey You What If?
Series 1: 25. You Could Switch Off The Sun?
See what would happen if you really could switch off the sun.
06-03-2026
CBBC
Hey You What If?
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.
26-02-2026
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 ...
18-06-2025
CBBC
Hey You What If?
Series 2: 22. You Had Kangaroo Legs
Running a marathon is hard. At least it is for a human. But what if we could swap our legs with an animal – would that make it any easier? \n\nFirst, we try ...
17-06-2025
CBBC
Hey You What If?
Series 1: 24. You Took All The Water Out Of The Sea?
Empty the oceans and you’d see hidden wonders, but you’d also cause the end of the world.
05-03-2026
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 ...
19-06-2025
CBBC
Hey You What If?
Series 1: 9. The Moon Was Made Of Cheese?
Things don’t quite go to plan when the moon turns into cheese.
05-02-2026
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.
02-02-2026
CBBC
Hey You What If?
Series 2: 19. You Only Ate Burgers
If everyone in the world ate nothing but cheeseburgers, we would run out of land, and even if we went meat-free, we would have to invent some crazy burgers to get the nutrients ...
12-06-2025
CBBC