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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!
Source: CBBC
Most recent episodes of Hey You What If?
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!
27-11-2025
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?
13-11-2025
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.
29-10-2025
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.
24-10-2025
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?
23-10-2025
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!
22-10-2025
CBBC
Hey You What If?
Series 2: 2. You Walked Through Walls
Wouldn't it be cool to be able to walk through walls? From turning into a gas to quantum trickery, we discover why it wouldn't be quite as useful as you'd like.
21-10-2025
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!
20-10-2025
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.
11-07-2025
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.
20-06-2025
CBBC
Most popular episodes of Hey You What If?
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!
01-11-2023
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!
14-06-2022
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?
19-12-2024
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.
22-10-2024
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.
15-03-2024
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.
11-07-2025
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.
23-05-2025
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.
29-10-2025
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?
13-11-2025
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?
23-10-2025
CBBC