Summary:
Watch Ruben poke a straw through a potato and think about these questions:
• Do you think this experiment would work with all potatoes and all straws? How could you check your prediction?
• Why does the straw go through the potato?
Captions:
Music
Ruben Meerman: Alright, well I better tell you what I brought with me today. I've got some experiments for you using this amazing liquid called liquid nitrogen.
It's incredible. And, it's in this bottle. You can't see it at the moment. I'm going to show it to you soon.
But, before I do these experiments with liquid nitrogen which are fantastic fun I thought I'd show two experiments that you can do yourself that you don't need liquid nitrogen for
so that this afternoon when you go home you can do a least a couple of my tricks. Then once we've done those we'll do some amazing stuff that you can't repeat yourself but you'll love watching them.
So, how about we start with a really simple experiment using a potato.
Children: Laugh
The second thing you will need for this experiment is a straw and the experiment is, or the trick is, to poke a straw straight through a raw potato as though it's a hot knife going through butter.
But that's not a hot knife. That's a flimsy little plastic straw.
And that's not soft, gooey butter, that's a raw, hard potato. So how on earth can you get this little straw through a raw potato.
Well I'm going to show you how to do it. But when you do it you might like to let your audience inspect your potato first because if I was to just do the trick you might think I've been sneaky
and somehow made it easier to get the straw through the potato and one way to do that would be to cook the potato, right then it goes nice and soft.
Could someone here in the front row, mate would you mind grabbing that potato and making sure that I haven't cooked it. Can you give it a squeeze. What's your name?
Kaelen: Kaelen
Ruben Meerman: Kaelen can you give it a good squeeze and make sure it's not cooked. Does that feel like a normal, raw potato?
Yeah. Thank you very much, Kaelen's our potato policeman today. Thank you very much.
Can someone check that I'm not tricking you with straw because sometimes people think that I've been sneaky with the straw.
Would you mind having a look inside that straw? Make sure there's nothing hidden in there. A normal straw. Everything's hunky dory. What's your name?
Andrea: Andrea
Ruben Meerman: Andrea. Thank you, Andrea. Andrea the straw inspector today, thank you. So, we know that I'm not tricking you, now can you see I've got a straw here with one of these spoons on the end?
Well, you don't need that spoon bit so I going to chop that off. There we go.
Children: Laugh
Ruben Meerman: Put that in the bin later. So now I've just got a normal straw and a normal potato. And, I'm going to poke the straw straight through the potato. And it'll go all the way through.
When you do it, an adult audience will be watching this and they'll be thinking no when the straw hits the potato it's just going to crumple up
and it's going to as though it's hitting a brick wall right but well let's see how it works.
You've got to wear a glove. So I'm going to put on an old gardening glove. And you hold the potato between your index finger and your thumb.
You hold the straw like a dagger and then you line it up. You hit it as hard as you can.
On the count of three I'm going to smack the straw in there. Let's see if it goes through. Are you ready?
Ruben and children: One, two, three.
Ruben Meerman: Hey, look at that. It goes all the way through. It's incredible. Now when you show some adults this they'll be amazed and they'll want to know how does this trick work because no one expects it to right?
So you need to be able to explain it to them. And I reckon you already know how this trick works or a big part of it because it's all to do with the shape of the straw. What do we call that shape? It's a big, long …
Children: Cylinder.
Ruben Meerman: Yeah, very good. And cylinders are very strong if you try to squash between your fingers like that. All cylinders are really strong in that direction.
They are not very strong if you try to bend them in half like so. And they are not very strong if you try to squash them across their walls. But if you try to squash a cylinder this way, they're really, really strong, right.
So that's the first thing. Second thing is it's made out of very, very thin plastic. And being thin makes the straw very sharp.
So this is a strong, sharp object which easily cuts through a potato. Can you see the little round hole in that potato there? I can see straight through that. Hello.
Which means there's a bit of potato stuck inside my straw which means we can do a very second funny part funny thing with this trick which only really works with these straws with the spoon on the end.
Every straw can get through a potato. This second part you're better off with a slightly stronger straw. Watch this.
Every time you do it a bit of potato gets stuck in the straw. So if I do it heaps and heaps of times the straw will fill up and bits of potato are going to go shooting out everywhere.
So that should be pretty funny. You ready, here we go. One, two, three. Did you see that bit go flying backwards?
Children: Yes
Ruben Meerman: Where did it go? Did it land on the floor? Oh well we'll just keep going. Hang on. Other end.
Children: Laughing. It going over there.
Ruben Meerman: It's going all the way over there. There's chips flying everywhere. I can't see any more. If you want to make chips with a straw you can. Sounds amazing doesn't it?
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Summary:
As you watch the video, think about the following questions:
• Why are plastic bags so bad for our environment?
• How can we reduce the number of plastic bags in the environment?
Captions:
And for this trick you need a plastic bag and you need some water, so you need a plastic bag that's waterproof. Right, so we're going to put a little bit of water in this bag.
You would use a tap. I don't have a tap here so I'm going just going to do it straight out of this bucket of water. Here's a bag full of water.
And the second thing you need for this trick is a nice sharp pencil.
Children: Uh, oh.
Ruben Meermen: Uh oh, what's he going to do here. Yes I'm going to do exactly what you think I'm going to do. I'm going to poke a pencil through a plastic bag full of water.
Sounds like a crazy thing to do doesn't it? Because, if you are like me you'll be expecting the plastic bag to burst open and water to go flying all over the floor.
But I what were you going to say mate, you had your hand up.
Child: My brother's done it and it didn't splatter anywhere
Ruben Meermen: And it didn't leak. Well the first time I saw it if you are anything like me you would have thought that the plastic bag will burst open and water will go flying everywhere, right.
But well I'm so confident in this trick that I'm going to do it over my own head.
Children: oooooo
Ruben Meermen: Am I going to get drenched? Let's find out. On the count of three.
Ruben and children: One, two, three
Ruben Meermen: Uh oh, hey. I didn't get wet. Look at that, it's not leaking. That's amazing and hang on maybe I did it wrong. I'll just grab some more pencils.
Here's a whole bunch of them. We'll stick a few more through. No, still not leaking. What about down the bottom there. No not leaking.
What if we go through at an angle? No, still not leaking. It's amazing.
Now this trick gets me every time because I always expect a plastic bag to do what a balloon full of water would do.
With a balloon full of water it would burst open right and water would go all over the floor and you would make a big mess.
But the reason this plastic bag doesn't burst open is because it's a completely different material and I think you already know why the bag doesn't burst open.
If you think about this plastic for a minute and have a think about what would happen if you tried to tear this plastic bag in half. If you tried to tear it, without water inside it.
If you tried to tear this plastic, it doesn't tear like a piece of paper tears does it. Before it will tear, what will it do? It will stretch.
Children: Stretch
Ruben Meermen: Stretch, yes. Because this material stretches before it tears, that's how the trick works. The tip of your pencil makes a little tiny hole in the plastic.
But as you push the pencil through the little tiny hole doesn't tear around the pencil, it stretches and makes a perfectly round waterproof seal.
Now do you want to see what happens when you take one of the pencils out?
Children: Yes.
Ruben Meermen: Uh, oh. I better go and do this over here 'cos it could be messy. How about I put that container there and that one there?
And let's take out the blue one. On the count of three, let's see what happens.
Ruben and children: One, two, three.
Ruben Meermen: Oh no.
Child: How cool's that.
Ruben Meermen: It's doing a wee wee.
Children: Laughing.
Ruben Meermen: Naughty bag, stop doing a wee wee. Oh look it's stopped. It's a toilet trained bag.
Children: Laughing.
Ruben Meermen: Good little bag. Now that's an amazing trick. I found this in a book actually. I didn't invent any of these tricks. Found this one in a book.
If you like doing these sorts of experiments go to my website. It's an ABC website, I'll give your teacher the address in a little while. You'll find heaps more of these experiments at my website
They are all free, easy to do with simple stuff. When you do this one though can you please use a plastic bag that you've already used for something else.
Don't use a brand new one because well it's a waste of a bag isn't it and plastic bags aren't very good for the environment so hopefully when you do it you'll use plastic bag that you've already used for something else.
And here a quick experiment that you might like to try yourself one time that shows you why plastic bags are bad for the environment. If you bury one of these in a garden bed next to a leaf off a tree.
Find a leaf that's about the same size as your plastic bag and then bury it side by side with the bag in about that much under the ground. Cover it up with dirt.
If you then wait for four weeks, it's a long experiment, you have to mark the calendar, but if you come back in four weeks and dig them up again you'll find that the leaf has almost completely disappeared.
It's gone. But it hasn't disappeared, it's been eaten by little insects, little beetles, worms, bacteria and they recycle all of the leaf back into the soil so the other plants can use it again.
There will be nothing wrong with it because there's nothing on planet earth that eats plastic bags. So there's no worms, no beetles, no nothing.
And it will still be there in four weeks, it'll still be there in four years. As far as we know, the plastic bag will still be there in four hundred years unharmed because nothing eats it.
So every time you use a plastic bag you're using something that you can't get rid of. So can you, hopefully use a plastic bag for this trick that you've already used.
And has anyone got any questions about any of that so far by the way. Or anything you'd like to tell me about science experiments that you like before we move on?
No. Shall we take all the pencils out?
Children: Yes
Ruben Meermen: Well let's see what happens when you do that. This could be messy. Well OK here we go. One, two, three. Oh, no look at that.
Children: Laughter
Ruben Meermen: That's a bit of a strange thing.
Child: The Surfing scientist is cool and amazing.
Child: The surfing scientist has cool experiments.
Ruben Meermen: .