Dark Adaptation

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In this activity (6th on the page), learners investigate how photoreceptors in the eye (rods and cones) "adapt" to low light conditions. Learners sort similar bottle caps in a well-lit room and then attempt to resort them in the dark. Learners will observe that many make mistakes in sorting in the dark. The lights will remain dim while learners discuss dark adaptations and how animals can see in the dark. After about 7-10 minutes, learners will separate the caps again in the same dim conditions as before and find that learners make fewer errors because the photoreceptors adapted to the low light conditions.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
10 to 30 minutes

Estimated Materials Cost:
free per student

Age Range:
Ages 8 - 18

Resource Types:
Activity, Demonstration


Materials List (per student)

  • Three sets of bottle caps (or other similar items)


  • Life Sciences
    • Diversity of Life
      • Animals
    • Evolution
      • Mechanisms of Evolution
    • Human Body
      • The Brain and Nervous System
    • Human Senses and Perception
      • Vision
      • Perception
  • Physical Sciences
    • Vibration and Waves
      • Light and Optics
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations

Informal Categories

  • Animals


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


  • Chudler, Ph.D., Eric H.


  • All rights reserved, Eric H. Chudler, 2009