Starring

You and Your Students!

Script By

Vicki Cobb, Education World Science Editor

Synopsis

Sip some cola and an “un-cola” (a lemon-lime soda) without seeing the color. You might be surprised that you can’t tell the difference.

Genre

Chemistry, The Senses, Nutrition

Props Required

• a cola
• an un-cola (for example, 7-Up or Sprite)
• water
• straws
• plastic cups
• blindfold
• nose clips
• measuring cups, measuring spoons
• ice
• ingredients to make your own cola drink:
  sugar, vanilla extract, powdered cinnamon, bottled sweetened lime juice, club soda

Setting the Scene (Background)

Colas and un-colas (for example, Sprite and 7-Up) are all citrus-based drinks.

Most "best guesses" about Coca-Cola's secret formula include one or more of the following ingredients: citric acid, sodium citrate, lemon, orange, and lime.

One obvious difference between colas and un-colas is the color. Cola has caramel color added (which doesn't affect the taste). Would a person who can't see the color of a cola and a clear soda be able to detect the difference? That's what this test is about.

Every cola manufacturer has a formula for its particular brand of cola syrup, and those recipes are very closely guarded secrets. Legend has it that only three people in the world know the recipe for Coca-Cola syrup. I thought you and your students might like to try to mix your own version, so I'm giving you a recipe to play with.

Stage Direction

Show-Biz Science is scripted by popular children's book writer Vicki Cobb. Click to learn more about Vicki or to read a brief synopsis of her philosophy of teaching science. Visit our archive of archive of Show-Biz Science Activities. Watch for a new activity each week. Then chat with Vicki -- share your feedback and ask your questions about teaching science -- on our special Showbiz-Science message board. Be sure to visit Vicki's Kids' Science Page for more great science fun, a complete list of her books, and information about how you can invite Vicki to come to your school. And don't miss her library of science videos too. Or visit Vicki and other great authors of nonfiction for children at the INK Think Tank.

You might want to do Act I as a demonstration. Once students have seen the demonstration, they might want to work in pairs or small groups to verify that it “works.”

The Plot

Act I
Choose a student to help you with this demonstration. Have the student put on a blindfold; secure it in place so you are certain there can be no peeking.

Pour two glasses of soda with ice: One glass should contain a cola, the other an un-cola such as Sprite or 7-Up. Ask your blindfolded volunteer to alternate sips between the drinks. Important: The mouth should be rinsed with water between sips. Switch the glasses around several times, and don't let onlookers give any clues to the sipper. If your subject can tell the difference easily, try it again using the nose clips.

Taste sensitivity diminishes with age. Your students might want to try this at home on their parents and other adults to test out this idea.

Act II
Use the ingredients below to mix your own cola:

• 1 tablespoon sugar
• 1 teaspoon vanilla extract
• 1/8 teaspoon cinnamon
• 1/2 teaspoon bottled lime juice
• 1/2 cup club soda

Try the same blindfolded taste test comparing commercial cola with your homemade version. The blindfold is important, since the two cola versions will look so different.

Behind the Scenes

The taste difference between colas and un-colas is real, although it is much less than most people think. Some of your subjects will be better at telling the difference than others. A nose clip will make telling the difference more of a challenge since smell is an important component to our experience with food and drink. One major difference between these two kinds of soda is sweetness. Which kind is sweeter? (usually the cola).

If some of your students are interested, you can carry the synthetic cola activity further by having them perfect the formula. They should systematically vary the amounts of the ingredients and have a blindfolded friend check each mixture against real cola. For example, keep everything in the same proportion but vary the amount of sugar by half-teaspoonfuls until the homemade soda is a sweet as the commercial brand; then vary the amount of lime juice by half-teaspoonfuls; and so on.

The End

For more information and activities for teaching about fields of force, check out
Sources of Forces: Science Fun with Force Fields
by Vicki Cobb, illustrated by Steve Haefele (The Millbrook Press, 2002).

Article By Vicki Cobb
Education World®
Copyright © 2006 Education World

01/14/05