• Using poster board, make a large flashlight cutout. To check for student understanding, give students two sticky notes each. Ask them to write any additional questions they have about light and place them on the cardboard flashlight. Spend time going through students’ questions and plan time to answer the questions or make clarifications.

In advance: Prepare the wavelength board the day before students come to class. You will need a white poster board divided into sections similar to handwriting paper. Set up the wavelength board to represent each color of the rainbow, measure each wavelength, and plot the points so that students can connect the wavelength. Use the following measurements to plot the wavelengths: red 6.5 cm, orange 5.9 cm, yellow 5.7 cm, green 5.1 cm, blue 4.8 cm, and violet 4.0 cm, or you can devise measurements of your own. Students will come to the Wavelength Board and draw the waves, using color markers/pencils of the visible spectrum. (adapted from Fairfax County Public Schools, “The Energy of Light and Sound,” “Making Waves,” and “Color Waves” activities)

Draw a rainbow on the board. Ask students to write the names of the colors of the rainbow and one thing they learned from the video they viewed for homework. To refresh students’ memory, show a small portion of The Electromagnetic Spectrum (running time 2 min. 15 sec.) for homework: https://www.youtube.com/watch?v=kfS5Qn0wn2o .

Ask students the following question, “What instrument was used to split the white light into colored light?” (prism)

“Now that we know that a prism bends light, we can investigate the wavelengths within the color spectrum.” Introduce students to vocabulary such as trough, crest, peak, and wave. Show students the following video clip Exploring Light and Color Video (running time 4 min. 25 sec.) http://videos.howstuffworks.com/hsw/9943-exploring-light-and-color-the-nature-of-light-video.htm

Explain that the visible spectrum includes various colors that move at different speeds. The speed at which they move determines their color. Red has a faster wavelength than violet. (Note: some references include seven colors in the visible spectrum, while others do not include the color indigo.) Students should work in cooperative learning groups for the following experiments.

Wavelength Lab: Experiment #1: Making Waves

Hand out copies of the Wavelength Lab Experiment #1 (S-5-2-2_Wavelength Lab.doc). Allow students time to conduct the lab.

Now ask student volunteers to come up and complete the wavelength board. Based on what they know about the order of ROY G BIV, ask students to justify why they are using a specific color. They should also identify the crest, trough, and measure the wavelength using a metric ruler. When the wavelength board is complete, students should be able to see that red has a faster wavelength than violet.

Before students begin the next experiment, show this short video clip, Color. Access it at the Web site Brainpop at https://www.brainpop.com/science/energy/color/preview.weml.

Access the activity page connected with this video and make copies for your class to use as an extension at the end of the lesson. When students have free time, they can take the online quiz.

Experiment #2: Wavelengths

Hand out copies of the Wavelength Lab Experiment #2 (S-5-2-2_Wavelength Lab.doc). Provide ample time for students to conduct the experiment. Remind students to record their observations. Observe and monitor students as necessary.

Experiment #3: Mixing Colors

When students have recorded their observations from Experiment #2, tell them they will now use colored plastic to filter the light from a flashlight. Hand out copies of the Wavelength Lab Experiment #3 (S-5-2-2_Wavelength Lab.doc).

Extension:

• Students performing above and beyond the standards can do math problems to determine the properties of waves.

Formula for calculating wave speed:

wavelength (m) / wave period(s)  =  wave.speed (m/s)

Length = 10m, period = 1.5s, speed = _________

Speed = 5m/s, period = 2.5s, wave length = ___________

Wave length = 20m, speed = 10m/s, period = __________

• Students requiring further practice with the standards can create a poster of a wave, labeling all the parts listed below. They should then demonstrate a wave with a short wavelength and a long wavelength by using a long rope held by two students.
• Parts of a Wave

• Crest – highest point of a wave
• Trough – lowest point of a wave
• Wave Height – vertical distance between the crest and the trough
• Wavelength – horizontal distance between two crests or two troughs
• Wave Period – the time between the passage of two wave crests at a fixed point