states of matter

Cooling Fans

This experiment came from Diane in South-central Pennsylvania. She and her son were discussing ceiling fans, and how they make you feel cooler. They wanted to know if the fan actually cools the room, or does it just feel that way?

Clear Ice

This experiment is the result of my forgetfulness. I took a tray of ice cubes out of the freezer, used half the cubes and then forgot to put the tray back in the freezer. When I remembered, the cubes were half melted. Only the centers of the cubes were left, and that ice was very cloudy.

Changing Pressure

Quite a bit of my travels involve changes in altitude. Going from sea level to over 7000 feet makes a big difference. As you go higher, the air pressure is less. This can do bad things to the stuff in your suitcase, such as causing shampoo to squirt all over your clothes. It would be nice to fly all of you up into the mountains to do this experiment, but I can't quite afford that right now. Instead, we will cause a change in air pressure by heating and cooling it.

Cartesian Raisins

One of the fun things about thinking up new science experiments is combining two or more old ideas into one new one. This time, we will combine the Dancing Raisins activity with the Cartesian Diver.

Breathing Hot and Cold

One of the most common questions that I get is where do I get the ideas for these experiments. Some are old classics that I try to give a new angle. Others are the result of questions sent to me by subscribers. Some of the ones that I like the best are the ones that just pop up, seemingly out of nowhere. This is one of those. It also comes with its own story, which makes it even better.

The story is one of Aesop's fables. If you have never read any of these, go read some. It is well worth the time.

Lightning in Johnson Canyon

This week we had a marvelous electrical storm to the west of our house. It was far enough away to make Junie Moon the Dog happy, but near enough for some nice photos. Since it was night, I used the same settings that I use for star photography. I put my Nikon D7000 on the tripod, with an 10-70mm lens. I set it for manual exposure, and set the shutter for a 30 second exposure, and turned on long exposure noise reduction. I hooked up my PClix, a marvelous device for taking photos at set intervals. Then I just let it click away.

Changing How We Look at Changing

I love it when teachers ask questions! I alway enjoy a good science question because they make me really think about the subject to be sure I give the right answer, but when a teacher asks a question, I feel obligated to give an answer (if I can) that will let them explain the subject to their students. Recently, I have been talking with a teacher friend, about chemical and physical changes, and the more we talked, the more I thought the rest of you might find this useful.

Bad Chocolate?

I mentioned that I had a lot of fun experimenting with carbonated soda (and drinking it) and that I should do an experiment with chocolate. I got quite a few e-mails suggesting experiments with chocolate, but this one was the most common. It has to do with the white discoloration that you sometimes find on old chocolate.

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