Question Video: Identifying Shapes That Match a Description Mathematics • 1st Grade

There is a mystery shape in this bag. Which clue will not help you guess the name of the shape? [A] It has 5 corners. [B] It is green. [C] It has 5 straight sides. Based on these clues, what is the shape in the bag? [A] Square [B] Triangle [C] Pentagon

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Video Transcript

There is a mystery shape in this bag. Which clue will not help you guess the name of the shape? It has five corners, it is green, or it has five straight sides. Based on these clues, what is the shape in the bag? Is it a square, a triangle, or a pentagon?

Are you feeling like a shape detective? Well, you’re going to need to be one with this question because we’re told we have a mystery shape in the bag. And like any detective, we’re given some clues to help us solve the problem. But not all of the three clues are useful. We’re asked, which clue will not help you guess the name of the shape? Now, all these clues are true about our shape, but not all of them are useful. The first clue talks about the number of corners that our shape has. The second clue talks about its color. And our third clue talks about the number of straight sides that it has. Which one of these clues isn’t very useful at all?

It’s the color, isn’t it? Knowing the color of a shape doesn’t help us tell what it is. Some circles are green, some triangles are green, any shape at all could be green. Knowing that the shape is green is not going to help us at all. If we want to be true shape detectives, we need to use clues like the number of corners that a shape has, and here we’re told that it has five corners, and also the number of straight sides that it has, and we’re told that it has five straight sides. In the second part of the question, we need to put these clues to the test.

Based on these clues, what is the shape in the bag? Is it a square, a triangle, or a pentagon? Now, one shape might jump out straightaway as being wrong. We can see straightaway that the triangle is the only shape that isn’t green. So we do know that the answer is not going to be the triangle. But it would be a shame if we cross the triangle off our list straightaway just because it was the wrong color. As we’ve said already, the color of a shape isn’t something we can rely on.

So let’s think of our two clues that really matter. It has five corners, and it has five straight sides. How many corners does a square have? One, two, three, four corners, not five. And we also know that a square has one, two, three, four straight sides, not five. The shape in the bag is not the square. As we’ve already said, we know that the shape isn’t the triangle cause it’s red. But let’s look at the more important clues. Triangles have three corners, not five, and three sides, not five.

This only leaves us with the pentagon. A pentagon, it’s a shape that has one, two, three, four, five corners. And we can count one, two, three, four, five straight sides. Of course, the pentagon is green as well. But it’s not this clue that helped us. As any good shape detective knows, we can tell a shape by the number of straight sides that it has and the number of corners or vertices that it has. The clue that did not help us guess the name of the shape was, it is green. So we used the remaining two clues, it has five corners and it has five straight sides, to help us identify the mystery shape as the pentagon.

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