The Light Spectrum

• 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: 

• • 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.