Color of Stars Properties of Dust Telescope Allocation Committee Astro-Madness Delta, Delta, Delta Hot Air Spectroscope Mirror, Mirror

Subject: Physics and Physical Science
Grade Level: 9-12

Materials You Will Need
Per student lab group

• Wax paper sheet


• graph paper (1/4 inch ruled with blue ink)


• protractor


• scientific calculator (like a TI-30)


• Laser pointer


• binder clip big enough to grip the laser pointer and hold down the “on” switch.

• Knox gelatin (8 x 7 ounce envelopes)


• desert gelatin with sugar (like Jell-O®) in red (strawberry) and yellow (pineapple).


• cookie sheet (1/2 to 3/4 inch deep, smooth and non-stick surface) or brownie pan (8 x 8inches, 2 inches deep).

Guides and Worksheets
Download, print and photocopy these lesson documents for your class.

Teacher Lesson Plan 195 K
Student Worksheet 79 K
Data table and plotting grid 47 K
Experimental Diagrams (for teacher) 43 K
Experimental Diagrams 46 K

Overview
Can gelatin (like Jell-O) change the speed of light? What is the index of refraction for gelatin that you can buy in a grocery store? Students will investigate the refraction properties of gelatin to calculate its index of refraction and discover that as the light travels through the gelatin, its speed and wavelength also change. This activity offers students a challenge to find the index of refraction of an everyday, intriguing, translucent substance outside the standard listing of materials and refraction indexes. During this activity, student must apply their knowledge of mathematics and physical science to calculate the gelatin’s index of refraction.

What Students Do
Students measure the angles of refraction of laser light traveling through gelatin, then plot their data to calculate the gelatin’s index of refraction.

You may choose from two different “Elaborate” activities:

Gelatin Stack: students formulate a hypothesis and design a simple experiment to test it.
The “Super” in Super Gelatin: students calculate how the wavelength and speed of light change inside the gelatin.

Note: Please download the PowerPoint presentation that goes with this lesson plan. It contains illustrations designed to help you and your students understand the directions for this lesson.

*TEKS are Texas Essential Knowledge and Skills. For more information, visit http://www.tea.state.tx.us/teks/.