Video Transcript
Liam is making a symmetrical
pattern. He has drawn his mirror line. What shape should he put in
position A? Which position should he put the
green diamond in?
In this problem, we’re told that
Liam is making a symmetrical pattern. We’re also told that he’s drawn his
mirror line. And you know, a mirror line is a
clue as to what makes a pattern symmetrical. We know that symmetrical patterns
are the same on either side of a mirror line. Just like a mirror reflect our face
back at us, we could say that the mirror line reflects the shapes. If we start with the top-row shapes
to begin with and we put our finger on the mirror line, whether we move it to the
left or to the right, we’ll see the same shape.
Liam’s put a yellow square on
either side of his mirror line. He’s made his pattern
symmetrical. Can you see he’s done the same with
the bottom two shapes he’s chosen too? He’s chosen a blue triangle on
either side of his mirror line at the bottom. Now, at the moment, we can see four
missing shapes, A, B, C, and D. It’s almost as if Liam hasn’t quite
finished his symmetrical pattern, has he? Let’s help him complete some more
of his pattern by answering these two questions.
Firstly, we’re asked, what shape
should he put in position A? If we look at position A, we can
see that it’s the next shape along to the yellow square on the top row. Can you see what we need to use to
help us? We need to look back across the
mirror line and see which shape is next door to the yellow square on the other
side. It’s a blue triangle, isn’t it? And if we put a blue triangle in
there to check, it looks right. This shape is the same on both
sides of the mirror line. It’s the second shape along.
In the second question, we’re given
a shape and we’re asked which position Liam should put it in. We’ve only got positions B, C, and
D left. Which position should Liam put the
green diamond in? The first thing we can do is to
find the green diamond in Liam’s pattern. Can you see it up here on the top
row? Now, for Liam’s pattern to be
exactly the same on both sides of his mirror line, can you see where he needs to
place the green diamond? At the moment, it’s on the top row,
furthest away on the left. So, the other green diamond should
also be on the top row, furthest away on the other side of the mirror line. This is position B.
We know that Liam’s pattern is
symmetrical because it’s the same on either side of his mirror line. To keep his pattern symmetrical, we
know that the shape that he needs to put in position A needs to be a blue triangle,
and he also needs to put the green diamond in position B.
