Variables and controls

Ice and Soda

This week's experiment came to me from my good friend Bob Cox. He told me about the trick and wanted to know why it worked. It took some thought and testing to come up with a theory of what is happening and then several e-mails to experts to confirm that I was on the right track.

Viscosity

Today I was so busy having fun that I put off working on this week's experiment. I had several ideas bubbling around in my brain, but nothing quite came together. Then, as I often do when I am looking for an idea, I picked up the first thing I saw and began playing with it. It happened to be a bottle of liquid soap. I turned it over and watched as the bubble rose slowly through the thick liquid. I knew that I had this week's experiment. You will need:

OJ Ice Crystals

This experiment comes from some of my wife's creativity. Our hotel has breakfast every morning, and she has been putting some extra orange juice in our freezer each morning. By evening, it is nicely frozen and ready to be eaten. Besides being delicious, it also offers a great lesson on the science of freezing. To try this, you will need:

Food Web Tag

Grasshopper on flower

Food Web Tag is a classic game that helps people understand how food webs work, letting them see how changing one thing can cause changes across the food web. You can play with as few as 5or 6 people, but it is much better if you have at least 15. To try this, you will need:

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