Question Video: Matching 3D Shapes to Nets Mathematics

True or False: The 3D shape, here, can be made from the net, here.


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.

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