Scale Drawing of the Visible Light Spectrum

Objective

Students will understand the relative sizes of the different waves in the visible light spectrum.

Big Idea

Students will understand that visible light is just one part of the overall light spectrum.

RAP - Review and Preview

5 minutes

I call students to the gathering area. I ask them to recall the different colors of the light spectrum. I ask them to recall the different ways light reacts in the environment:

1. reflection
2. refraction
3. blocked by opaque materials
4. partial penetration by translucent materials
5. penetrates transparent materials.

I tell students that today we are going to make a scale drawing of the visible light spectrum. Light wavelengths are very small and are sometimes difficult to comprehend so, by magnifying the spectrum we can compare and contrast the wavelengths of the different colors of the spectrum.

Guided Investigation

25 minutes

I divide the class into groups of 2 or 4. Each group gets one set of materials in a box. Each group receives several sheets of paper: red, orange, yellow, green, blue, violet, white, and black. Students have a metric ruler with millimeter markings, scissors, scotch tape, black marker.

I explain to students that light waves are measured in nanometers. For example, red on the spectrum, is 700nm. For reference, the diameter of a penny is 19 billion nanometers, so it is VERY small. Students will scale their diagrams so that 1nm = 1mm. I provide students with a data sheet, where they can make the conversions for themselves before they measure and cut their paper.

I tell students that they will cut their colored paper into 1-inch strips. They will then measure each color according to the length calculated on their data table. Colors will be taped together one below the other so that the longest wavelength is on the top and the shortest is on the bottom. Students will label each strip with its length in nanometers.

When students have completed their models, they can work together on the critical-thinking questions on the bottom of the data sheet.

Wrap Up

10 minutes

I call students to the gathering area. I ask students to report, which wavelength was the longest and which was the shortest. I ask students to answer the critical-thinking questions too. This is a great way to assess students’ ability to estimate.