Illusion Lab Log: Measure-It Record Book

An illusion lab log for young scientists: write down your guesses and measurements, work out your error with a simple formula, survey friends and family, keep a moon diary with the little-finger test, draw your results graph and design your own size illusion.

What’s inside:

- Working out your error, with a worked example

- My measurements: two guess-v-measure log pages

- Find-the-middle survey for friends and family

- Grown-ups v kids survey

- Moon diary (2 pages)

- My results graph

- Design a new size illusion

- Credits, licence & sources

Pages: 11 (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. Fill-in pages (logs and surveys) can be printed as often as you need for your own family or class.

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. There are no photos in this pack. 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.