Breaking Light Apart

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Objective

Students will understand how light filters work and how white light is broken up to show different colors.

Big Idea

Students will understand that although we see white light, colors come from filtering or absorption of color.

RAP - Review and Preview

5 minutes

I call students to the gathering area. We review that we have talked about what light is, we have drawn a scale drawing of the visible light spectrum and discussed how much of the light spectrum we cannot see. We also looked briefly at how different eyes are adapted to use light depending on where they live and what they need for survival.

I tell students that today we are going to look at white light and play with how to break it apart into the spectrum. 

Guided Investigation

15 minutes

Students follow along with a PowerPoint about breaking light apart. We talk a little about how we bent white light to show its spectrum. Today we will mix colors and filter colors.

I walk students through slide 9 in the presentation. When we get to slide 10, I offer students the chance to experiment with filters.  

Independent Investigation

15 minutes

I use cheap Dollar Store flashlights with LED bulbs to ensure white light. We use colored cellophane for filters. I have red, green, magenta, and blue cellophane for filters. Students follow the examples I give them. Students work in pairs or fours and record their own observations.

After students have completed their observations, I offer them time to experiment on their own as well.

Wrap Up

5 minutes

I call students back to the gathering area and we talk about how some filter colors absorb colors and let other colors through. We talk about their observations and I record them on a poster paper.  After all observations are recorded, we look to see if there are any patterns to which colors are blocked or allowed through different-colored filters.

I ask students to make observations about primary and secondary colors. Is there a way that primary colors act that is different from secondary colors? I often ask the Art teacher to teach a complimentary unit on primary and secondary colors at the same time. This helps students to understand the difference.