The Light Spectrum

Junior (Age 9 – 10)

Curriculum Goal

Grade 4: Understanding Light and Sound

  • Investigate the characteristics and properties of light and sound. 
  • Demonstrate an understanding of light and sound as forms of energy that have specific characteristics and properties. 


  • Students are put into groups of two or three. 
  • The following activities will help students understand the properties of the light spectrum by visually examining two interactive systems. 


Activity 1: 

  • Cell phone or another source of white light 
  • Different shapes of glass cups 
  • Water 
  • White piece of paper 

Activity 2: 

  • Coloured crayons, pencils, and a ruler 
  • String  
  • White piece of paper 
  • Cardboard 
  • Compass 
  • Scissors and glue 


  • Groups will take turns completing Activity 1 and Activity 2. Students will record their findings at each station for a class discussion.  

Activity 1:  

    • Fill a glass with water and set it on the desk so that it is lined up with the edge of the white sheet of paper. 
    • Shine the light source onto the glass, experimenting with different positions and angles until you see a rainbow on the piece of paper. 
    • Experiment with different shapes of glasses and record your findings noting any similarities and/or differences.  
    • Write down why you think you are or are not noticing any changes.  

Activity 2: 

    • Using the compass, draw a circle on the piece of paper and on the cardboard. Then cut those out. 
    • With the ruler, split the circle into 3 equal sections. Colour the sections using the green, red, and blue crayons. Paste the piece of paper onto the cardboard. 
    • Punch two holes with your pencil near the center, leaving approximately 6 cm between the two. 
    • Loop the string through the holes and tie the ends together, as shown in this image: 

Light Spectrum

    • Center the cardboard on the string and twist it until both sides of the string are twisted on your fingers. 
    • Observe what happens to the colours on the wheel as you pull the strings to unwind them. Ask students to record their observations and explain what they see.
  • After the students are done, discuss as a class the findings. Explore potential explanations 
  • For Activity 1 – Encourage students to think about the purpose of the water. What was it doing to the white light? 
  • Observations may include the following: the water was bending the light; the water was splitting the light into its constituent colours. 
  • For Activity 2 – Encourage students to think about the rotating wheel as a combination of the colours blending into white.

Look Fors

  • Do students recognize white as a combination of all the colours of the spectrum?
  • Are students making explicit connections between the two activities?
  • Have students understood light can be split into their base components or added together to form different experiences for our eyes (colours)?

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