Symmetry: slide, flip and turn
Find lines of symmetry, complete a mirror picture and learn the three moves: slide, flip and turn. Read one step, play with it, then tap “I understand this”.
Lines of symmetry
A shape is symmetrical if you can fold it on a line so that the two halves fit exactly on top of each other. That line is a line of symmetry.
The fold test
Choose a shape. Guess how many lines of symmetry it has, then tap the button.
Test it with paper: cut out the shape and fold it. Do the edges match exactly? Then you have found a line of symmetry.
Every point on a circle is the same distance from the centre. Whatever line you draw through the middle, the two halves are exactly the same. That is why there are endlessly many.
Complete the mirror picture
In a mirror picture (reflection) every point is just as far from the mirror line as its partner, only on the other side. Count the squares from the line.
The mirror grid
Tap the squares on the other side of the red line to make the mirror image. Then tap “Check”.
A square that is 1 square from the line has a mirror image that is also just 1 square from the line. Do not count from the edge of the grid.
A mirror shows everything as far behind the glass as it is in front of it. If you stand 1 m in front of a mirror, your image seems to stand 1 m behind the glass. That is why we count from the mirror line, not from the edge.
Three moves: slide, flip and turn
A transformation moves a shape. In all three of these moves the shape stays the same size and keeps its shape:
- Slide (translation): the shape glides to a new place and still points the same way.
- Flip (reflection): the shape is turned back to front, like in a mirror.
- Turn (rotation): the shape turns about a point, like the hands of a clock.
The movement lab
Tap the buttons and watch how the shape moves.
Slide, flip and turn only move the shape; they do not stretch or squash it. Every side stays the same length and every angle stays the same size. The new shape is congruent to the old one: exactly the same shape and size.
Which move was it?
Move detective
Look at how shape A got to B. Is it a slide, a flip or a turn?
Correct: 0
Ask two questions. Does B point the same way as A? Then it is a slide. Is B back to front (left and right swapped)? Then it is a flip. Otherwise it is a turn.
Tessellations
A tessellation covers a floor with shapes without gaps and without overlapping. It only works if the corners that meet at one point make exactly 360°.
Tile the floor
Choose a shape and see whether it tessellates.
A full turn around a point is 360°. If the corners of the tiles that meet there make less, a gap is left. If they make more, one tile must lie over another.
Check yourself
- A line of symmetry folds a shape into two halves that match exactly.
- Mirror image: every point as far from the line, on the other side.
- Slide = translation, flip = reflection, turn = rotation. The size stays the same.
- Tiles fit without gaps if the corners at a point make 360°.
Write these points in your maths book. Read them again the night before the test.
Quick questions
Tap an answer. If you get one wrong, read why and go back to that step. You get new questions every time.
You ticked all 5 steps! Now you are ready for the quiz.- Practice sheet for this classQuestions + memo · 2 A4 pagesPractice sheet
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Ready for more? The Grade 5 symmetry quiz gives you new questions every time.
- One step a day is enough. Ten calm minutes work better than an hour the night before the test.
- Look for symmetry together at home and outside: a leaf, a butterfly, letters on a sign. Ask: “Where would you fold it?”
- Ask your child to tell you the rule in their own words. If they can explain it, they understand it.
- The ticks (“I understand this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 5 Maths. Always check your teacher’s notes and textbook too.