Video Transcript
This pattern is symmetrical. What shape is missing?
If we’re given a repeating shape
pattern, we often look at it from left to right, and we notice part of the pattern
that keeps repeating itself. But if we look at this pattern from
left to right, we can’t see any parts that are repeated again and again. That’s because this isn’t a
repeating pattern. Instead, we’re told that this
pattern is symmetrical. What does it mean for something to
be symmetrical?
We know that for something to be
symmetrical, we can draw a line through the middle of it and it will be the same on
both sides. Now, for a pattern to be
symmetrical, it must also be the same on both sides. But where’s the middle of our
pattern? Where could we draw a line where
the pattern is the same on both sides? Can you see where we could draw our
line? This wouldn’t be right, would
it? On one side of the line, we’d have
a green rectangle and on the other side, a yellow square. This isn’t a line of symmetry.
This looks more like it. On both sides of the line, we can
see a yellow square. And as we move outwards, the
pattern changes in exactly the same way. We then have two green
rectangles. Now, we can see on the right-hand
side of our pattern, there’s a missing shape. But we can use our knowledge of
symmetry and how the pattern changes to work out what this missing shape is.
Can you see what it’s going to
be? After the green rectangles come the
blue triangles, only we haven’t got a blue triangle on the right-hand side, have
we? But as soon as we sketch it on, we
can see that our pattern now looks symmetrical. We found the center line of our
pattern, and we made sure that it looked the same on both sides of this line. Our missing shape is a blue
triangle.
