Lesson video

Hi, it's me, Mrs. Jones.

Hopefully, you're ready to do some maths together with me today.

Today we've got some fun problems lined up all about finding the mass of objects.

Let's have a look at today's learning.

Today we're going to be finding the mass of objects in units.

We'll be measuring the masses of objects and we'll also be making some predictions about how heavy we think an object is.

After that, you've got an independent task, and finally, an ends of lesson quiz.

You'll just need a pencil and piece of paper to help you do your task later on today.

If you haven't got one already, you can pause the video now to get everything you need.

Once you've got everything, let's begin the lesson.

Hmm, here, I've got a button.

I'm going to use this button as a non standard unit of measure.

So I'm going to use this button and some other buttons to help me measure how heavy I think this shape is.

What is this shape? Do you know what it's called? Well I can see it has some triangular faces.

It's a pyramid.

Now, my buttons, I'm not always going to refer to them as buttons, because we're using them to measure, I can refer to them as a unit.

One button is equal to one unit of measure.

Okay, shall we make a prediction? When we predict something, we think about how much we think it will weigh, but we don't know the answer yet and then we can always check afterwards.

Okay, I'm going to make my prediction.

I predict that the pyramid will weigh the same as around five buttons.

Do you want to have a go at making a prediction? Your prediction doesn't have to be the same as mine.

Let's have a look.

Oh, I wonder if my prediction was correct.

Here I've got my balance scales and I can see the scales are now balanced, meaning these must have the same mass.

How many units does the pyramid weigh? Can you count them? Off you go, have a count and see if you can tell me.

I can see that the pyramid weighs one, two, three, four, five, six buttons, or we can say six units.

Pause the video now to see if you can say that in a full sentence.

My turn your turn.

The pyramid weighs six units.

Here I've got a different non standard unit of measure.

Before I was using buttons but I don't have to use buttons, I could use marbles.

I could use several marbles in order to help me measure.

But I couldn't use a mixture of marbles and buttons, because my units need to all be the same.

Hmm, I wonder what would be the same and what would be different if we measured the pyramid using marbles instead? What do you think would change? Let's see if we can make a prediction about how many marbles the pyramid would be.

Pause the video now and explain that.

Let's have a look.

Wow! Here I've got a balance scale that's just looking at my two units, I can see that the marble is heavier than the button.

So if the marble is heavier, perhaps our pyramid will have will be the same as fewer marbles than it was buttons.

Perhaps we won't need as many marbles.

Mmh, I'm going to make a prediction.

I think the pyramid will weigh four marbles, four units.

Let's have a look.

Oh, we can see the pyramid weighs this many marbles.

Can you count them? It weighs four marbles, or four units.

My prediction this time was correct.

It doesn't matter if my prediction isn't correct, we're just doing a sensible guess and now, we've checked our answer.

Hmm, this time, I want to find out the mass of an apple.

I was thinking I could use paper clips.

Do you think paper clips would be a sensible unit of measure? Or can you think of something that might be more useful? Hmm.

Now I know that paper clips of that are quite light in comparison to an apple.

If I held a paperclip here, it would be a lot lighter than my apple.

And I would predict that we would need lots and lots of paper clips in order for these to weigh the same.

Now I'm not sure if I have lots and lots of paper clips, so I might need to use a different unit of measure.

I've got some choices here.

I could use some buttons that I've got, some cubes or some marbles.

Which do you think might be the most sensible unit of measure to measure an apple? Hmm.

We could use any of them really but again, buttons and cubes are quite light so we would end up needing quite a lot of them to weigh the same as an apple.

I think a marble, which is a little bit heavier, but not as heavy as an apple might be a sensible unit of measure to use.

I wonder how many marbles would weigh the same as my apple? Here we have a banana.

I want you to have a go at making a prediction.

We're going to be using marbles as our unit of measure.

One marble is equal to one unit.

Now, let's make a prediction.

Here's my prediction.

I predict that the banana will weigh six marbles or we could say, six units.

Let's have a look to see if I was right.

Hmm, I'm not sure but let me just check and count them.

One, two, three, four, five, six, seven.

The banana weighs seven units, which is seven marbles.

Interesting.

My prediction wasn't quite quite correct this time, but it was quite close so I was using some mathematical thinking when I was doing it.

Let's have a look at another.

Here we've got a key.

I predict that the key will weigh four marbles.

Let's see if I'm right.

Here we go.

One, two, three, four.

This time my prediction was correct.

The key does weigh four marbles.

The more I do some measuring and the more I test out the weight of different objects, the closer my predictions are getting, because I'm getting a good sense of how much objects weigh.

For your task today, you've got a reasoning problem.

We're using marbles as our unit of measure.

One marble is one unit.

We've got two bags here.

I want you to investigate and think about which bag do you think is heavier.

We can see this bag, there are no marbles.

But in order for it to weigh the same, we have to add three marbles to this bag.

Mhh, your job is to write an explanation today, or say your explanation out loud and ask your parents or carer to help you write it down.

There's also a second part to your task.

This time you're looking at some boxes.

Again, your need to write an explanation or ask your parents or carer to help you write an explanation after saying it out loud.

This time which box is heavier? Box A or Box B? Look closely at the marbles and see if you can work it out.

Then you've got Box C or Box B.

This time there aren't any marbles.

You need to make sure you explain how you know.

Once you've finished your independent task, you can come back to the video and we'll go over the answers together.

Pause now and go and complete your task.

Hopefully you've had a go at your task by now and we're going to go through the answers.

Are you ready? Okay, looking at our two bags for part one of the task.

I know that this bag needed one, two, three marbles in order for it to weigh the same as this bag.

This bag must have been the heaviest bag because we needed to add these three marbles in order to make it balance.

Let's have a look at part two.

Hmm, looking at our boxes, this one had to have two marbles.

This one only needed one marble.

This one is the heaviest, Box B.

Here we've got my explanation.

Box B is heavier than Box A, because the scales are weighted and it has fewer marbles.

Hmm, Box C is heavier than Box B.

I know this because there are no marbles now.

So we can see that Box C lower on the scales and it must be the heaviest box out of them all.

Hope you had fun today, if you'd like to, ask your parents or carer if you can share your work today.

Once you're all done, make sure you go off and do our multiple choice quiz to end the lesson.

I've loved working with you today.

Hope you've had a good time.