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.
