The size illusions shop
Fact-checked printables for the kitchen table and the classroom, plus a short list of books and measuring kit. Every purchase helps keep this site free.
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Size illusion printables
Fact-checked PDFs in A4 and US Letter, sold as instant downloads from the ReallyByte store.
Draw Your Own Size Illusions: Step-by-Step Sheets
Ten classic size illusions to draw with a ruler and compass, from the Müller-Lyer arrows to the Ponzo railway, each with measured steps, a practice grid and the trick explained
Size Illusion Puzzle Pack: Measure, Spot & Solve
Guess-then-measure challenges, “which is bigger?” puzzles, a maze, a word search and a crossword, all with answer keys
Make-and-Test Size Illusion Experiment Cards
Twelve experiment cards for the kitchen table or the classroom: the coin test, the moon trace, a shoebox peep-show and more, each with what to look for and why
Illusion Lab Log: Measure-It Record Book
Record your guesses and your measurements, work out your error, test friends and family, and keep a moon diary
Don’t Trust Your Eyes! Kids’ Size Illusion Worksheets
For ages 6 to 11: guess and measure, spot the trick, draw an illusion, illusion maths, a maze and colouring, with answer keys
Classic Size Illusions Poster Set
Six fact-checked posters: Müller-Lyer, Ebbinghaus, Ponzo, the moon illusion, the Ames room and the T illusion
Best valueThe Complete Size Illusions Printables Bundle
All six packs plus a guide, A4 and US Letter, in one download.
Free sample
Try before you buy: a free 8-page size illusions sample, with a drawing sheet, a puzzle, an experiment card, a lab log page, a worksheet and a poster from the packs. A4 PDF (960 KB) or US Letter PDF (948 KB).
Books & kit
Affiliate links: As an Amazon Associate I earn from qualifying purchases. These are Amazon UK search links, not endorsements of particular products. Read reviews and pick what suits you.
Books
- Optical illusion books (affiliate link)Big picture books of classic tricks, to flick through and argue over.
- Illusion books for children (affiliate link)Lots of pictures, not many words, plenty of “no way!”.
- Books on how we see (affiliate link)For grown-ups who want the why, not just the wow.
Measuring
- A good steel ruler (affiliate link)The one tool every size illusion fears.
- Digital calipers (affiliate link)Measure circles and gaps to a tenth of a millimetre.
Drawing your own
- Geometry sets (affiliate link)Compass, protractor and ruler for drawing your own illusions.
- Fineliner pens (affiliate link)Crisp lines make sharper illusions.
- Dot grid paper (affiliate link)Perfect for drawing equal lines that won’t look equal.
Experiments
- Clear acetate sheets (affiliate link)For tracing the moon at arm’s length, as the Exploratorium suggests.
- Dry-wipe markers (affiliate link)To draw on the acetate, and wipe it clean for the next full moon.
- Craft straws (affiliate link)For the Exploratorium’s shoebox size-and-distance experiment.
- Binoculars (affiliate link)For a closer look at the moon, high or low.
Puzzles and kits
- Optical illusion jigsaws (affiliate link)A thousand pieces of not believing your eyes.
- Illusion science kits (affiliate link)Make-and-test kits for the kitchen table.