MUSIC PLAYING
Hi, everyone, welcome.I'm Greg, and this is…Mwaksy, where are you?Hello? Hello! I'm here!I'm sorry I'm late, I was setting up a demo. Sure!So, I have a number of bricks here in this wheelbarrow,and I have the same number of bricks here in this tray.But how come it's easier to lift the wheelbarrowcompared to lifting the…tray…?!
Well, Mwaksy, the reason for thatis because the wheelbarrow is a clever use of a lever.A lever? How does that work?OK, so, a lever is simple machinethat helps you lift something by providingwhat's called a "mechanical advantage".Essentially, it's a way to lift heavy stuffusing less effort.There are three main parts to a lever.You have a load that you're trying to lift - that's all your bricks.There's a pivot point that the lever turns or rotates around,for your wheelbarrow, that is here.And then there's the effort you apply,the force needed to move the load.Oh. OK, I think I've got that.But I've also noticed, it's easier to lift the brickswith the handles at the top,compared to when I try and lift it…at the bottom…!Yup.
So, do you have a demo to explain why that is?I do indeed. OK, awesome!Show me the science!Right, I've set up a very simple machine for us.Yeah, it looks simple.
SHE LAUGHS
This is a super-powerful lever, I think you'll find!So, the lever is this ruler here.Here is the pivot point that the lever is going to rotate around.Here is the load that we're going to trying to liftand then, we're going to measure the effort, the forcethat it takes to lift that load with this cool little gadget.It's called a spring scale or a Newton meter.Ooh…Here is my question for you… No!OK! Is it going to take more effort, more force,to lift that load from point A,which is closer to the pivot point,or point B, which is further from the pivot point?Hmm…? Hmm! OK, I feel like,when I was lifting the wheelbarrow,it took more force to lift closer to the pivot pointthan it did when I was further away.
So, I'm thinking! I'm thinking it will take more force to liftfrom point A than it would from point B. I like it.That's my answer. Shall we try it?Yeah. OK, all right, here we go. Hook this on here.All right, if you can read it off for me.Sure. Lifting. Lifting, lifting…That says 4.OK, 4. OK.4 Newtons.OK, we'll go to the end. OK. Moment of truth.
MWAKSY IMITATES FANFARE
Ooh, that one says 2.Wait, I was right! I was right! Yeah! Oh, my gosh!Yeah, spot-on.So, the further away you can apply that effort, that force,the easier it is to lift a loadbecause your lever is longer. OK!We're learning. I'm learning. He already knew.Levers are great, OK? Agreed.But what can we use them for other than lifting bricksand lifting rulers? Loads of things!So, yeah, we've seen that we can use them to lift something,like with your wheelbarrow or, say, with a wheelie bin.We can also use them to open things like drinks bottlesand lots of tools use levers, as well, to do loads of things.A pair of scissors is actually two levers in one.So is a seesaw.
Anything with a load, an effort and a pivot is a lever, right?Yeah, spot-on.Once you know what to look out for,you're going to start seeing levers everywhere!It is amazing how powerful and useful levers can be.So, do we have time for just one more demonstration? Oh, I think so!Really? OK. OK, this one involves marshmallows, OK?What I need you to do is get a marshmallow from one side of thetable to the other side using the smallest amount of force possible.OK, I don't know how I'm going to do thatbut I feel like levers are involved.You bet! OK! This is a little catapult that I've made, here.The marshmallow is going to go on the end of the catapultand you're going to pull it down like thisand see what happens.And you can see why we're using marshmallows,cos they're soft and small.If you use anything bigger and heavier,then it might get a little dangerous.Also, these are tasty!Exactly!OK, so, we have the pivot here, we have the load here,and then I am going to apply effort at the top here.Yeah. So, are you ready? I'm so ready. And boom! Whoa!
BOOOOM!
DISTORTED SOUND: BOOOOOOOOM!
I'm so happy with everything that we've learnt today… Good stuff.…and I'm really excited to have a marshmallow. As a little treat.Exactly. But do you have a question for them to discuss?Yeah, I do. OK, try this.Could you catapult a rocket into space?Oh, that's a good one. I'm going to have to start thinking about that.
HE MURMURS TO HIMSELF
It's been fun!Goodbye, everyone! See ya!
Video summary
Mwaksy and Greg design and make mechanisms that use levers to allow a smaller force to have a greater effect.
Greg shows Mwaksy an example of a lever, using a Newton meter to measure the force needed to lift the load from different points.
After learning about where levers can be found, Mwaksy and Greg use their knowledge about levers to catapult marshmallows into the air.
Show Me the Science is a series of short films and teacher resources for primary schools, following presenters Mwaksy Mudenda and Greg Foot as they use demonstrations, experiments and animations to learn about forces and electricity.
Teacher Notes
Before watching the film:
Prior to this lesson you may wish to introduce students to other relevant topics, for example:
During the film:
Depending on your lesson’s focus, you may wish to pause the video at certain points to check for understanding, asking questions such as:
- Mwaksy found it easier to lift the bricks in the wheelbarrow. Can you think of other examples like this where you have used a lever to lift something, or a lever has made things easier for you? (wheelie bin, suitcase)
- Apart from lifting things, what else can we use levers for?
- What do you think would happen if we didn’t have levers?
Final question:
Could you catapult a rocket into space?
Discussion points for the final question:
- Do you think we can catapult a rocket into space?
- How could we do this from what we have learnt about levers?
- Why would this be useful? (reducing how much fuel we use, less impact on the environment, could cost less money)
- More recently, scientists have been looking at ways in which we can catapult rockets into space
Following on from the film:
- Can you name any levers in your school? (Scissors, doors, seesaws etc.) You can link this to other subjects, such as the tools that are used in Design and Technology. Can you label the load, pivot point and effort in each of these? You can label the objects or draw a diagram/picture and label it.
- You can make your own catapults! Scouts UK have instructions for a similar version to the one that Mwaksy and Greg used. Students can talk about where the load, pivot point and effort is on the catapult design. You can make it more challenging by adding an obstacle that your load needs to go over.
- This can be linked to learning about how people used catapults in history such as the trebuchet.
This short film is suitable for teaching science at KS2 in England, Wales and Northern Ireland and 2nd Level in Scotland.
What is gravity? video
Mwaksy and Greg learn about what gravity is using bottles and air rockets.
What is friction? video
Mwaksy and Greg learn about friction, air resistance and water resistance, and see them in action.
What are magnets? video
Mwaksy and Greg learn about magnets, where they come from, and where magnetic materials can be found.
