Solids, flat shapes and position · Usually met around P1
Mirror pictures
Mirror it: as far from the line on the other side.
How to do it
Method
Mirror it: as far from the line on the other side
3 squares on the left, 3 mirrored on the right: 3 + 3 = 6
Another way
Fold and check
Fold on the dashed line: the sides match exactly
In full
A symmetric picture folded along a line matches exactly on both sides; the line is its line of symmetry. To finish a symmetric picture, “mirror” each square across: a square against the line stays against the line, and one two squares away lands two squares away on the other side. So the pattern flips over; it is not slid across. Or imagine folding the paper on the dashed line, and check square by square that the two sides match.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
Fold along the dashed line: the shaded squares on the two sides match exactly.
True or false?
Show the answer and working
Answer: False
Check square by square: every shaded square needs a shaded partner just as far from the line on the other side.
Example 2
This picture is finished so that it is symmetric about the dashed line. How many squares are shaded in the whole picture then?
Show the answer and working
Answer: 8 squares
4 on this side and 4 mirrored on the other: 4 + 4 = 8.
Example 3
This picture is finished so that it is symmetric about the dashed line. Then how many shaded squares touch the dashed line, on both sides together?
Show the answer and working
Answer: 4 squares
2 shaded squares touch the line on this side; mirrored, they still touch it, so 2 on the other side too: 4 in all.
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