Symmetry is a favourite topic for the SAT papers and this is a typical question. Four patterns of shapes are given and if a shape has symmetry mark it with a tick, if not, mark it with a cross. A maximum of 2 marks if all patterns of shapes are marked correctly. Interestingly, although it states that a tick or a cross must be used, other options will gain the marks.
Two marks are also given if:
a. If two correct are ticked and incorrect two are not marked at all.
b. If correct lines of symmetry are drawn and the other two shapes left blank.
c. If other alternative and unambiguous signs are given eg Y and N.
One mark is given if three of the four diagrams are ticked or crossed correctly.
Children are usually given a small mirror to help with symmetry questions. The mirror can be placed along potential lines of symmetry and look from either side. If it is symmetrical the shape will look like the original.
Without a mirror, it is a little trickier. Probably the best way is to draw a potential line of symmetry on the shape and imagine what it would be like if folded along the line. If one half would fit exactly over the other it is symmetrical.
- © 2009 Maths Blog