Make-and-Test Size Illusion Experiment Cards

Twelve make-and-test size illusion experiments for the kitchen table, the classroom and the night sky: make two coins match, build a shoebox peep-show, test the moon four ways, trick friends with a two-pencil T and a square top hat, swap the Jastrow shapes and run a grown-ups v kids survey.

What’s inside:

- How to use the cards, with the rules of a fair test

- Twelve experiment cards, two to a page, each with what you need, what to do, what’s going on and space for what you saw: the coin test, the silhouette version, a shoebox peep-show, the little-finger moon, between your legs, trace the moon, find the middle, the two-pencil T, the square top hat, Jastrow cut-outs, grown-ups v kids and Ponzo on the tracks

- Templates page with the Jastrow shapes, the Ebbinghaus circles and a railway photo

- Credits, licence & sources

Pages: 10 (including cover and credits). Sizes: A4 (210 × 297 mm) and US Letter (8.5 × 11 in), both PDFs included in one zip.

Printing: Print at 100% / actual size on A4 or US Letter, so the drawings keep their true measurements. Inside pages use light backgrounds and print well in black and white; covers are dark, so start from page 2 to save ink.

Every fact is checked against Michael Bach’s Optical Illusions & Visual Phenomena, Encyclopaedia Britannica and the Exploratorium (checked 31 Oct 2026), and the sources are listed on each pack’s credits page. The railway photo is a CC0 image via Wikimedia Commons; all drawings are our own. Drawings, puzzles and layouts are REALLYBYTE’s own work. Not endorsed by Michael Bach, Britannica or the Exploratorium.

Licence: personal and single-classroom use. You may print as many copies as you need for your own family or your own class, and share it with your class through a password-protected platform. Please don’t resell, re-upload or share it publicly. For school-wide use, please email info@reallybyte.com.

Made by REALLYBYTE, the team behind size.illusions.im. Questions: info@reallybyte.com

This is a digital download: no physical item will be shipped.