Making Rainbows

Overview:

Students will learn about white light, waves and rainbows. They will explore these concepts by wearing diffraction glasses.

Time: 

Prep: 5 minutes

In class: 1 hour

Budget:

costs about $35 for about 100 people

Lesson Materials:

*You can use the document in the link below to either: tailor the experiment to your needs or to have a printable version of this lesson plan*

Making Rainbows Lesson Plan

The plan is editable and printable. Copy the Google Doc in your own drive and make edits or you can just print.

Making Rainbows Lesson Video:

Learning Objectives:

  • Identify that white light is comprised of all the colors of the rainbow.
  • Identify that white objects reflect all the colors.
  • Identify that black objects absorb all the colors.
  • Identify that eyes see reflections of other colors. 
  • Begin to define “absorb,” “reflect,” and “waves.”

Materials Needed:

  • 1 pair of diffraction glasses
  • Mirror
  • Paper wadded up (1 green, 1 red, 1 yellow, 1 orange, 1 blue, 1 purple)

Experimental Methods and Discussion:

  1. Where do we see rainbows?
    1. Rain
    2. Garden hose
    3. Shower
    4. Water and light
  1. Sunlight is a rainbow:
    1. Water and another medium such as a prism can split apart the light.
    2. Always have in the same order: red, orange, yellow, green, blue, indigo, violet 
    3. Light moves so fast that our brain interprets all of those colors as white. 
  1. Pass out diffraction glasses
    1. Explain how the light has been split apart so we can see the rainbow.
    2. Little lines in the glasses bend the light. Since the colors are moving at different speeds, the go around that small barrier at different speeds. This is what splits up the light.
  1. The colors we see are due to absorption and reflection:
    1. Reflection – light bounces back like a mirror (or a ball).
    2. Absorption – light goes into the material.
    3. White objects – all colors reflect back.
    4. Black objects – all colors are absorbed and we are not seeing any light.
    5. Without light we cannot see anything. We do not see “thing” – we are seeing light.
    6. Red objects absorb everything, but red is reflected.
  1. Demonstrate the reflection and absorption concept with a rainbow of colors moving in slow motion:
    1. Wad up color papers (red, yellow, green, blue, purple, orange) – these can be the light. 
    2. Have the wadded up papers hit a white surface (like a white paper). Have all of the colors bounce back and direct it to the audience’s eye.
    3. Have the wadded up papers hit a black surface (like a black paper). Have all of the colors absorb (or go behind the object). Explain that black objects have absorbed all the colors and are not bouncing back to the eye. 
    4. Repeat the procedure with other color objects. For example, hold up a green water bottle. All the colors hit and are absorbed into the green water bottle, except for the green reflecting back out. 
  1. Light travels in a wave:
    1. Every color has a wave with a different frequency.
    2. Light travels so fast that our brain sees it as white.

Project Extension:

Move onto the Newtonian color wheel project to generate “white light” from the colors of the rainbow.

Logistics:

STEAM Subjects: 

  • Science (Physics)

General Topics:

Nature, light, diffraction, rainbows, waves

References:

Suggested Reading:

  • Light Waves by David Adler and Anna Raff – Best for kindergarten
  • Discover Science Light by Kim Taylor – supplemental
  • Investigative Science: Why Does Light Cast Shadows by Jacqui Bailey

Suggested Viewing:

  • Ask the StoryBots. “Why is the sky blue?” Season 1, Episode 4. Netflix, August 12, 2016.
  • Bill Nye, the Science Guy. “Light and Color.” Season 2, Episode 7. PBS, December 24, 1993.
  • Nature Cat. “Tally Ho! A Rainbow” Season 1, Episode 9a. PBS, January 18, 2016. 
  • Tumble Leaf. “A Rainbow in My Room”.” Season 2, Episode 14b. Directed by Drew Hodges. Written by Karl Geurs. Amazon Prime, December 10, 2015

Funding:

CSU Internal Funding Sources:

  • IRA (Instructionally Related Activities Fund)
  • Faculty Small Grant

External Funding Sources:

  • Adobe