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Video transcript of Episode 3: Shrinking Coin

Below is the full transcript of Episode 3: Shrinking Coin delivered by IOP's Lucy Kinghan.


On-screen text reads: "Do Try This at Home from the Institute of Physics. Episode 3: Shrinking Coin."

Camera cuts to a close-up shot of Lucy, who is holding a coin in one hand, and a piece of paper with a coin-sized hole in in the other hand. Lucy looks at the coin on her left and then the paper on her right saying: "2D... or not 2D?" 

Camera cuts to a medium shot of Lucy. She is sitting behind a table. There are a couple of coins, a pencil, a pair of scissors, and some paper on the table.

Lucy: "Hello and welcome to Do Try This at Home brought to you by the Institute of Physics. We’re making these films because we want to help parents and carers in the UK and Ireland get their kids excited and curious about the world around them – and you don’t even need to leave your home to do it.

"My name is Lucy and you’re very welcome to join me in my home. I’ve managed to find a quiet enough corner so you can join me on a journey to the third dimension in a demonstration that I like to call the Amazing Shrinking Coin." 

On-screen text reads: "Lucy Kinghan, IOP Public Engagement Officer (Ireland)."

Lucy: "For this demonstration, you’ll need a 10 Cent coin and a 2 Euro coin. If you’re in the UK, you can switch this with a 1p and 2p coin, so long as you have one small coin and one large coin to work with. You’ll also need a pencil, a pair of scissors and some small pieces of paper. To get started, we’re going to take our 10 Cent coin and we’re going to lay it in the centre of the paper. Using our pencil, we’re going to trace around the coin." 

Lucy places the smaller 10 Cent coin in the centre of the paper, and holding it down with her first finger, whilst drawing around the edge of the coin with the pencil. She then sets the pencil and coin aside.

Lucy: "Next, we’re going to cut from the centre of the circle, so that we’re left with a piece of paper with a hole in the middle." 

Lucy picks up her scissors and carefully pokes a hole into the centre of the circle she has drawn. She then cuts a hole in the centre of the paper, following the circle that she drew, whilst she rotates the paper. She removes the disc of paper and is left with a piece of paper with a round hole in the middle.

Lucy: "Now you can demonstrate to your family that the 10 Cent coin can easily slip through the hole. 

Lucy holds the paper up and drops the 10 Cent coin through the middle of the hole. We hear the coin clatter on the desk. Lucy then picks up the larger 2 Euro coin."

Lucy: Challenge them to try to do that with a 2 Euro coin. So, see if they can get the 2 Euro coin to fit into the 10 Cent size hole without ripping or tearing the paper. It also might be a nice idea for everyone joining in if everyone had their own coin and piece of holey paper so they can try it a few times. And then you can show them how it’s really done. 

The camera changes angle and we hear a swishing noise to show that Lucy is about to explain how the experiment works.

Lucy: "Bending the paper creates a third dimension, so we can turn our round hole on a flat piece of paper into a slit across the bottom of a curved piece of paper. Of course, our problem is still there." 

Lucy loosely bends the paper in half, so that the bend is at the bottom and the hole is now a slit. Holding the two ends of the paper loosely together at the top, she then drops the bigger coin between the sides of the paper with her other hand, so that it rests on top of the slit. Although the coin can be seen, the sides of the slit are too close together to let the coin slip through the hole.

Lucy: "These points here and here are still too close together to allow the coin just to slip through, so this is where the creative bit comes in. Because we have folded the paper, we can very gently pull these points apart to allow the paper to fold like this and so it can get wider, without tearing, to let the coin slip through." 

Lucy holds the paper between finger and thumb near the bend, on either side of the coin. She gently slides her fingers upwards around the coin, so that the hole grows wider. She allows the paper to give way around the hole so that the coin slips through the hole.

Lucy: "Just like that old saying 2D or not 2D. A top tip if you’re doing this with your family is to use fresh sheets of paper because the folds in the paper might give them a clue. This demonstration is all about getting your family to think like a scientist and to help them improve their problem-solving skills. 

"If you’ve enjoyed watching this video, then do give it a like and then maybe head on over to our website. Thank you so much for watching and see you next time!"

On-screen text reads: "Do Try This at Home from the Institute of Physics. For instructions and more Do Try This at Home films visit These experiments have not been specifically safety tested for home use, but we believe them to be safe if the instructions are followed. Adult supervision is recommended as appropriate. All experiments are carried out at your own risk."