Through the Mirror
Which shape is the target reflected in the mirror line? Tap one and watch the ghost flip across.
This engine’s own main skill is Reflection. It practises reflect a shape alongside it.
A reflection in a vertical mirror swaps left and right and leaves top and bottom exactly as they were. That single rule kills every trap here. A rotation turns the shape round, so its top and bottom swap too. A translation slides the shape without changing which way it faces, so anything sticking out to the right still sticks out to the right. A flip in a horizontal mirror changes top and bottom instead of left and right. The safe method in the exam is to pick one distinctive corner, work out where the mirror sends it, and check the candidates against that single point before comparing the whole shape.
What to say if they get stuck
- A reflection swaps left and right but never turns the shape upside down.
- Pick one corner of the target, such as the step near the top, and ask which side of the shape it should end up on after the flip.
- Three of these are traps: one has been turned right round, one has simply slid sideways without flipping, and one has been flipped top to bottom instead of left to right.
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Spot the Changed Reading
Exactly one of these readings comes out different. Which one?
This engine’s own main skill is What Stays the Same When a Shape Moves. It practises reflect a shape alongside it.
The programme is “Slide 4 right”, then “Slide 2 right”, then “Flip in the line x = 4”. Every move on that list picks the outline up and puts it down without changing its size or shape, so the lengths of the sides, the angles at the corners and the area inside are all exactly what they were. What a rigid motion does change is WHERE things are, and here that is the coordinates of corner A. There is one more thing a flip changes and a slide or a turn never does: the letters ran anticlockwise round the outline and now run clockwise. The exam-safe habit is to sort every reading into "about the shape itself" or "about where the shape is": the first kind always survives, the second kind is the only place an answer can hide.
- Step 1. Watch it move. Play the cards and watch the readings.
- Step 2. The odd one out. Which single reading came out different?
What to say if they get stuck
- Tap a reading and it is drawn twice: once on the faint outline where the shape started, once on the solid one where it is now. Scrub slowly and watch whether the two marks stay the same.
- A slide, a turn and a flip all pick the outline up without stretching or squashing it, so every length, every angle and the area come through untouched.
- A flip is the only one of the three that reverses the outline, and this programme has one of them, so the letters end up reading round the other way.
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Which Card Was Played?
The move has already happened. Play each card on the outline and find the one that lands on the ghost exactly.
This engine’s own main skill is Identifying Transformations. It practises reflect a shape alongside it.
The move was “Turn 90° anticlockwise about (-4, 2)”. The card beside it, “Turn 90° clockwise about (4, 3)”, is the same kind of move, so calling it a turn settles nothing: what has to be read is which way round it turns, and which point it turns about. It comes down to one corner. A starts at (-1, -3) and the ghost has it at (1, 5); the other card sends it to (-2, 8) instead. That card does get one corner exactly right, which is why one corner is never enough on its own. That is the exam-safe method: settle what is different about the two cards, then pin it down with a single corner.
- Step 1. Look at it. Drag the track to play a card and watch where the outline goes. Scrub back to try another.
- Step 2. Name the move. Which card was played? Pick the one that lands the outline exactly on the ghost.
What to say if they get stuck
- Both cards play the same kind of move, so deciding it was a turn does not choose between them. What is different is which way round it turns, and which point it turns about.
- Follow one corner. A starts at (-1, -3) and the ghost has it at (1, 5), so the right card has to send it exactly there.
- Check a second corner before you lock in. The wrong card here lands one corner exactly where the ghost has it and every other corner somewhere else.
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