Video Transcript
True or false: The 3D shape, here,
can be made from the net, here.
Before we start this question,
there’s a word in this sentence that we need to remind ourselves of. What does the word net mean in
maths? We could say that a net is what a
3D shape might look like if it was opened up flat. Another way of saying the same
thing is that a net folds up to make a 3D shape. And the statement that makes up our
question contains a net too. Can you see the picture of it on
the end? This is like a plan of a 3D
shape. And if we cut this out of cardboard
and folded it up, it would make a 3D shape. But what sort of 3D shape? Because our statement shows a
picture of a 3D shape and it tells us that we can make this from this net. Now what do you think? Is this statement true or
false?
To help us, we could look very
carefully at the 3D shape and also at the net to find clues. What can we tell if we look at the
3D shape? Well, probably, the most important
thing that we could look for is the faces of this shape. And we can see just by looking that
all of the faces of this shape are rectangles. Now you might look at the faces on
each end and say, “Well, they look like squares to me.” Well in maths, a square is just a
really special type of a rectangle. So because we can’t be sure, we
could just use the word rectangles for now.
Now, let’s have a look at our
net. What shapes make up this net? This is really important because as
soon as we fold our net, these shapes are going to turn into the faces of the 3D
shape we make. Well, when we look closely, we can
see that this net is made up of three rectangles, so we can say some faces are
rectangles. But we can also see two triangles
on the ends. This is going to make a 3D shape
that has faces that are triangular too. Now we could count the faces. We could also imagine what this net
might make if we folded it, but we really don’t need to. We’ve answered the question. The net is going to make a solid
shape that has some triangular faces. But the 3D shape in the picture
doesn’t have any triangular faces. We can’t make this 3D shape from
this net. The statement in the question is
false.
