Size and Distance

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In this activity about depth perception, learners create an optical illusion in a shoe box. By looking through the viewing hole, learners explore how they can trick their brain into thinking that two similar objects of different sizes are really the same size. The trick is in the special construction of the box, and because their depth perception is impaired when they close one eye.

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
10 to 30 minutes

Estimated Materials Cost:
$1 - $5 per student

Age Range:
Ages 6 - 18

Resource Types:
Activity, Demonstration


Materials List (per student)

  • A shoe box with lid
  • 2 Straws
  • 2 Coins of different sizes (for instance, 1 quarter and 1 dime)
  • Modeling clay or Fun Tak™ reusable adhesive
  • Construction paper that contrasts with the inside of the shoe box
  • A piece of posterboard or similar-weight cardboard, a little larger than the end of the box
  • A knife or scissors
  • Adult help


  • Life Sciences
    • Human Body
      • The Brain and Nervous System
    • Human Senses and Perception
      • Vision
      • Perception
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations


To use this activity, learners need to:

  • see
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


This resource is part of:

Access Rights:

  • Free access



Funding Sources:

  • National Science Foundation
  • California Department of Education
  • NEC Foundation of America