Maths · What Stays the Same When a Shape Moves
Spot the Changed Reading
Exactly one of these readings comes out different. Which one?
Free to use and free to share. There is no sign-up, no score, and nothing a child does here is recorded or sent anywhere. What you may do with it, in full.
Loading the interactive exercise. Nothing you do here is saved or scored.
Why this works
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.
Helping a child through Spot the Changed Reading
It runs in 2 steps
- 1. Watch it move. Play the cards and watch the readings.
- 2. The odd one out. Which single reading came out different?
Hints, least revealing first
- 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.
When they finish it: “Spotted it!”
4 11+ skills this exercise practises
Each of these has its own page, with a worked example on it. 1 of the 4 names the mistake that skill attracts.
- Identify a shape propertyIdentify one stated property of a 2D or 3D shape.
- Preserve measure under a rigid transformationUse the fact that translation, rotation, and reflection preserve lengths and angles.
- Reflect a shapeIdentify the result of one reflection in a stated mirror line.
- Rotate a shapeIdentify the result of one stated rotation.
You can reuse this. Here is exactly how far that goes
Tutors, teachers and editors keep asking, so this is the answer in writing rather than by email. You do not need to ask permission, and you do not need to tell us.
- Embed it
- Put the exercise inside your own page with the code above. It stays playable, and it keeps working when we improve the engine behind it.
- Print it
- Print the page, or print the exercise off the screen, and hand out the copies. No limit on how many.
- Use it in class
- One child or a full set, in a school, in a tutoring session, in a homework club, or at the kitchen table.
- Put it in something you charge for
- A paid course, a paid tutoring session, a paid workbook, a members-only site. You owe us no fee and you do not need to ask.
- Reuse it in your own writing
- Quote it, rewrite it, translate it, cut it up, or build something different on top of it. Treat the wording, the worked examples and the question ideas as yours to work with.
The one thing we ask is a link back to the page you took it from, so a reader can find the live, playable version and the rest of the 11+ skills next to it. That is a request, not a condition: nothing above depends on it.
This covers the interactive exercises and the teaching notes on these 11+ pages. It does not cover the Trace Learn name or logo, and it does not let you present your version as something Trace Learn published.
Embed this exercise
Paste this into your own page and the exercise runs there, playable, for your readers or your students. It is 900 pixels tall by default and as wide as the column you put it in; change the height if your layout wants a different one.
The embedded copy has no header, no footer and no sign-up prompt. It records nothing about the child using it, on your page just as on ours.
Spot the Changed Reading touches 4 skills at once
Which means a child who struggles with it could be stuck on any one of them. A free diagnostic across all four subjects narrows it to the one.