Catch up TV
Series 1: 5. You Could Go on Holiday to Mars?
Experience the ultimate in long-distance travel - a holiday on Mars!
Source: CBBC
Most recent episodes of Hey You What If?
Hey You What If?
Series 2: 9. We Had Two Suns
There is a way that Earth could have a second sun, so we try it out to see what happens.
14-03-2025
CBBC
Hey You What If?
Series 2: 1. You Built A Mega Slide
Could you build a slide to the other side of the world? You would need to start in space, use the slippiest slide ever and make sure you have enough supplies before you go down it!
13-03-2025
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.
13-03-2025
CBBC
Hey You What If?
Series 2: 10. Your Mind Could Move Things
We imagine a world where it's possible to move things with your mind like films, but find that the laws of physics mean that this superpower wouldn't quite work like you'd expect.
12-03-2025
CBBC
Hey You What If?
Series 2: 3. We Got Rid Of Bugs
Bugs might be annoying, but we would soon regret it if we got rid of them - all our favourite foods would disappear, and there would be dung everywhere!
11-03-2025
CBBC
Hey You What If?
Series 2: 20. You Threw A Ball Round The World
To throw a ball around the world, you need to start out in space, throw it ten times the speed of a bullet and make sure your ball does not explode when it hits the atmosphere.
11-03-2025
CBBC
Hey You What If?
Series 2: 5. You Could Stop Global Warming
Imagine if we had a thermostat that could turn the world temperature down - could we fix global warming? But be careful, a few degrees too far could cause an ice age.
10-03-2025
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.
31-01-2025
CBBC
Hey You What If?
Series 1: 8. The Earth Stopped Spinning?
Find out why stopping the earth from spinning isn’t such a good idea.
30-01-2025
CBBC
Hey You What If?
Series 1: 7. Clouds Were Made Out Of Cotton Wool?
Clouds might look like cotton wool, but if they really were, things would get very messy.
29-01-2025
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.
20-12-2024
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.
31-01-2025
CBBC
Hey You What If?
Series 2: 14. You Built A Giant Sandcastle
Is it possible to build a sand castle the size of a real castle? We imagine how it could be done, using a pneumatic drill and a huge, solid gold steamroller!
30-08-2024
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.
28-01-2025
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.
13-06-2022
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!
27-01-2025
CBBC
Hey You What If?
Series 2: 16. Money Grew On Trees
If you had a tree that could grow money, would that make you rich? Even if you wait 20 years for your tree to grow, you will probably end up no richer than you started.
04-09-2024
CBBC
Hey You What If?
Series 1: 7. Clouds Were Made Out Of Cotton Wool?
Clouds might look like cotton wool, but if they really were, things would get very messy.
29-01-2025
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.
22-09-2024
CBBC
Hey You What If?
Series 2: 17. You Flew Like A Superhero
Flying like a superhero may sound like enormous fun, but there are some serious downsides that Hollywood does not tell you about - weather, extreme cold and even fizzy blood.
27-09-2024
CBBC