Lesson Video: Comparing: Heavier and Lighter Mathematics • Kindergarten

In this video, we will learn how to directly compare two objects by weight, using the words “lighter” and “heavier.”

07:42

Video Transcript

Comparing: Heavier and Lighter

In this video, we’re going to learn how to compare two objects by their mass or weight. And to do this, we’re going to use the words “heavier” and also “lighter”. So the words heavier and lighter are two words that we can use to compare the mass or the weight of different objects. Here’s a piece of cheese and a brick. Which is heavier? The brick is heavier than the piece of cheese. We could also say that the piece of cheese is lighter than the brick. The brick weighs more than the piece of cheese, but how do we know this?

Some people may say that they think the brick is heavier because it’s bigger. And you know this is often true. An aeroplane is bigger than a car and is heavier. But this isn’t always true. Which is heavier, the balloon or the carrot? Well, the balloon is bigger than the carrot, does that make it heavier? No, it doesn’t. The balloon is full of air, so we’re going to have to make sure that we hold onto that string to stop it from floating away. Even though it’s bigger, the balloon is actually lighter than the carrot. The carrot is heavier than the balloon.

Just because an object is bigger doesn’t always mean it’s heavier. We’re going to have to compare our lump of cheese and our brick another way. A balance is a good way of comparing the weight or the mass of two objects. We can see from this picture of a balance which object is heavier. The balance has gone down at the end with the brick on it. So the brick must weigh more than the lump of cheese. If we could hold the objects, we might be able to compare how heavy they are just by feeling them.

But even if we can’t actually hold them in our hands, we can still use our brains to come up with good questions to ask ourselves. Which object would you prefer to have in your school bag? We can compare the two objects in our heads and say we’d rather have a piece of cheese because a piece of cheese weighs less than a brick. Let’s see whether we can use what we know about objects now to compare their weight or their mass.

We can compare two objects using the words “lighter” or “heavier”. The elephant is heavier than the mouse. The mouse is lighter than the elephant.

Which animal is heavier? And then, which is lighter?

Let’s start by answering this first question, which animal is heavier? We can see a picture here of a balance. It’s a little bit like a seesaw. On one end, we have a cat. And at the other end, there’s a horse. And our question asks us, which animal is heavier? In other words, which animal weighs more? And I’m sure you know this already. But if we look at our picture, we can certainly use this to help us.

We can see that the balance or the seesaw has gone down on the end where the horse is. This is because if we compare the two masses or weights of these two animals, the horse is heavier. And of course, we know this without the picture, don’t we? You may have seen a friend or a neighbor picking up their cat and holding it in their hands. Have you ever seen anyone do that with a horse? Of course not. A horse weighs a lot more than a cat. The animal that is heavier is the horse.

Our second question shows another balance or seesaw, but this time we have two different objects on there. This time we have an apple and a watermelon. So we’ve got two pieces of fruit, and we need to compare how much they weigh. This time the question asks us, which is lighter? When an object is lighter than another object, it means it weighs less. We can see that the apple is a lot smaller than the watermelon. Does this mean it’s lighter? Well, just because something is smaller doesn’t always make it lighter. So we’re going to have to find a better reason than that.

Let’s look at the picture of our balance or seesaw. We can see this as soon as we put the objects on each end, the end with the watermelon on has gone down. And the end with the apple on has gone up in the air. This means the watermelon is heavier than the apple. The apple is lighter than the watermelon; it weighs less. And if we imagine what these two objects weigh, of course we’d much rather carry a bag of three apples than a bag of three watermelons. The object that’s lighter is the apple.

Which is lighter, a tree or a bunch of grapes?

In this question, we’re shown two objects, and we’re asked to compare them. We’re not comparing their size or their color. Instead, we need to compare how heavy they are because our question asks us, which is lighter? Lighter is one of two words that we can use to compare the weight or the mass of objects. And when something is lighter than something else, it weighs less. The other comparing word we often use is heavier. This is when an object weighs more. But our question asks us, which is lighter? Which weighs less, the tree or the bunch of grapes?

Now, you may have picked up a bunch of grapes before, but I’m pretty sure you haven’t picked up a whole tree. So how can we compare the weight or the mass of these objects. Well, in a way, what we’ve just said is a really big clue. Why haven’t you ever picked up a tree? Well, one of the reasons might be that it’s really, really heavy. A bunch of grapes is much lighter than a tree. Although grapes don’t grow on trees, they grow on plants that are a little bit like trees, where lots and lots of grapes grow together. So one bunch of grapes is definitely going to weigh a lot less than a tree.

We’ve used what we know about these objects to compare their weight or their mass. We know the tree is heavier than the bunch of grapes. And so we can also say the bunch of grapes is lighter than the tree.

So, what have we learned in this video? We’ve learned how to compare two objects using the words heavier and lighter.

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