cartoon drawing a schoolgirl blowing bubles into a glass of milk

 

Fun Food Stuff

Every Demo
an Experiment

Is Shaking needed
to make butter?

Better Bubbles --
Skim or Whole?

Make Milk Stiff

DNA Dance

Biotechnology in Food

DNA as Videotape

Menu for Workshops
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Which makes better bubbles, skim milk or whole?


Tom Zinnen, UW Biotechnology Center
and UW-Extension, 608/265-2420,
zinnen@biotech.wisc.edu

(This is page three of a seven-page sequence. If you did not start with page one, please go backand start with page one now)

How do you know you are blowing the same amount of air through both straws?

 How can you answer this question, just using the tools at hand?
Switch and repeat: Switch the position of the two cups, so one time the skim is on the left, and the next the whole is on the left. Do you get the same amount of bubbles each time?
Test the amount of air coming out of both straws: What are the possible outcomes when you blow through 2 straws at the same time? Straw A could get more air than straw B, straw B could get more air than straw A, or straw A and straw B could get the same amount of air. What do you have in front of you that could measure the amount of air?
boy blowing air into two glasses of milk through two straws at the same time. Expectations, Observations and Conclusions: What if you took 2 cups and put equal amounts of skim milk in each cup? If you blow the same amount of air through both straws, you expect to get the same amount of bubbles. If you blow different amounts of air, you expect different amounts of bubbles. Now, do the experiment and observe the bubbles. What do you conclude if you get the same amount of bubbles? What do you conclude if you get different amounts of bubbles?
You should also ask what's your "Batting Average?" If you blow 10 times into the two cups with the same type of milk, how often do you get the same amount of bubbles from both straws? Is practice important in science?

What are other factors that could affect bubblicity?

 Many people find that when they first compare skim and whole milk, both bubble about the same. When they repeat the experiment with the same milk samples 20 minutes later, skim bubbles but whole milk won't! Can you list all the things the milk has been exposed to during that 20 minutes? Graphic which gradually lists time, temperature, light, carbon dioxide from breath, plastic from straw, components of cup, air and asks if you can think of others
On the next page (page four) are some things to consider and test.
Go back to page two of better bubbles.