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Series 2: 13. You Were the Last Person on Earth
What would the planet be like if all other humans disappeared, leaving you as the last person on earth?
Source: CBBC
Most recent episodes of Hey You What If?
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?
09-03-2026
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!
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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
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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
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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
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: 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 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: 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
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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
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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
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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!
30-01-2026
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: 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