T.E.S.L.A. Lesson Plan: The Light Waved At Me

What is T.E.S.L.A.? Click here.

Objective: students will learn about light waves and play with light.

Materials:
piece of string or light rope about 2 yards long, one for every two students
piece of paper or posterboard
white ceiling, screen, wall, and/or blackout curtain
polarizing film (2 squares for each student, big enough to fit over the business ends of their flashlights)
a flashlight for each student (students can bring their own)
color gels (red, green, blue)
a light source for teacher to use (flashlight works fine; make sure it's bright)

Advance Prep:
Cut the polarizing film into squares; try all experiments first so you don't look like an idiot when something doesn't come off the way you wanted it to.

Lesson 1: What is a wave?
Select two students to hold the ends of one of the strings. Show the students how to make a wave. Explain what a wave is.

Experiment 1: make your own wave
Each pair of students gets a piece of string to make waves with. First, students have unstructured play with waves. Then students will be encouraged to make waves large and small, waves fast and slow. Then students will make waves that are small and fast, small and slow, large and fast, large and slow. Explain that small/large is called amplitude and fast/slow is called wavelength (fast wave = short wavelength). Encourage students to make waves up and down as well as side-to-side.

Lesson 2: Opaque and Translucent
Explain that light can travel through some things and not through others. Things that light can travel through are called "translucent". Things that light cannot travel through are called "opaque".

Experiment 2: What is opaque, what is translucent?
Students shine their flashlights onto various objects in the room to discover whether they are opaque or translucent. Students are amazed to discover that their hands, eyelids, and cheeks, as well as posterboard and grapes, are translucent.

Be sure to allow ample time for students to play the chasing-beams game with their flashlights. All children are contractually obligated to play this game for a minimum of five minutes whenever more than one flashlight is turned on in the same room.

Lesson 3: Light waves can be controlled
Explain that we see because light waves bounce off objects into our eyes. We can control what we see by controlling the light.

Experiment 3: polarizing film and gels
Students place two pieces of polarizing film over their flashlights, and then rotate one with respect to the other to observe color change. Explain that each layer of polarizing film is blocking light that is waving in one direction. Add a color gel to that mix and notice that the film can be rotated to block the light completely.

Please note that if the flashlights were turned off between Experiments 2 and 3, students will be obligated to play the chasing-beams game again.