Sliding Gray Step

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How can you make one shade of gray look like two? By putting it against two different color backgrounds! This activity allows learners to perform this sleight of hand very easily. They will be startled by how different the same color looks when its background changes.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
30 to 45 minutes

Estimated Materials Cost:
$1 - $5 per student

Age Range:
Ages 8 - 18

Resource Type:


Materials List (per student)

  • 1 sheet white paper, 8 1/2" x 11" (or use white poster board if you want to make the snack a little more durable)
  • 1 sheet black construction paper (size not critical, since you will be cutting it into strips)
  • paper cutter (if available)
  • ruler
  • scissors
  • glue stick
  • 1 sheet transparency film for overhead projector, 8.5 in x 11 in
  • gray electrical tape, 3/4 inches wide, or gray duct tape, 2 inches wide
  • paper clips


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


To use this activity, learners need to:

  • see
  • see color
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


This resource is part of:

Access Rights:

  • Free access


  • Rathjen, Don


  • All rights reserved, Exploratorium, 2009