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Churn, Churn, Churn

Starring

You and Your Students!

Script By

Vicki Cobb, Education World Science Editor

Synopsis

Make butter as a class activity. Learn about the science behind it.

Genre

Chemistry, Nutrition

Props Required

  • a large glass jar with a screw-top lid
  • heavy cream

Setting the Scene (Background)

Modern kids never see the origins of a lot of the stuff they take for granted. If you've never made butter in the classroom, you're in for a treat -- and for an eye-opening lesson in how much muscle-power it takes to turn a small amount of cream into butter. If you have made butter this way, you can put that activity into context by sharing two previous Show-Biz Science activities that teach students about emulsions:

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.
 

If you have a quart jar and make butter from a pint of heavy cream, you'll make enough for everyone to taste it on a cracker. You'll want to involve the entire class in this activity, because there's going to be a lot of shakin' going on! Everyone should take a turn.

The Plot

Act I
Follow the instructions below to make butter:

  • Pour enough heavy cream into a jar to fill the jar halfway.
  • Tightly screw on the lid and shake the jar. Have each class member take a turn shaking the jar. At first the cream will become thick, like whipped cream. Be patient. Keep shaking.
  • After about 10 minutes of constant shaking, the cream will become very hard to shake. It will stick to the sides of the jar. Keep shaking!
  • You will begin to see clumps of the thickening cream and butterfat stick together. You will see spaces on the sides of the jar. Keep shaking!
  • Suddenly, the thickening cream will become very easy to shake. Shaking has squeezed the buttermilk out of the butter, and the result sticks together in one big gob.
  • Spread the butter on crackers and eat it. (You can also drink the buttermilk.) It will be the best butter your kids ever ate!

Behind the Scenes

Heavy cream is an emulsion. The fat is spread throughout the cream in very tiny drops. The protein in the milk acts as an emulsifying agent; it keeps the fat droplets suspended. When you shake the cream you force the fat droplets to come together. If they come together with enough force, they'll stick to each other and keep forming bigger and bigger gobs until you've got butter.

The End

Use this activity in connection with two other activities that teach about emulsions:

There are two kinds of emulsions. The suspending liquid in an emulsion, also known as the enrober, can be either oil or water.

  • One kind of emulsion is a mixture of water in oil, like you made in the "Spheres of Influence" activity above. Salad dressing is another example.
  • The other kind of emulsion is an oil-in-water emulsion, examples of which include mayonnaise or heavy cream.

Cold cream, moisturizing creams, and hand lotions are all emulsions. They tend to feel like the enrobing liquid. Cold cream is a water-in-oil emulsion so it feels greasy or oily. Moisturizers and hand lotions are oil-in-water emulsions, so they will dry on your skin as the water evaporates.


Article By Vicki Cobb
Education World®
Copyright © 2004 Education World
 

09/24/2004