This is a repost of an item from my old blog.

The Twin Cities Home Schooling Creationist Science Fair at Har Mar Mall in Roseville, Minnesota happened last month. The organization that (at least partly) sponsors this event (Twin Cities Creation Science) usually posts photographs of the science fair, but this year they got into a tizzy about it for some reason and removed the photographs from their web site.

I was at the science fair, and I snapped a couple of photos, and I think there are interesting points of discussion that are lost with the TCCSA dropping the ball. Unfortunately, many of my photos are pretty low quality but there are a few that are usable.

This is the famous bunny poster that is central to a lot of the controversy. I actually think it was the cutest poster there. The wording (you can only see a little at the top) made with some kind of fabric glued on the poster was brilliant, and the bunny is as cute as a button. See this post for a discussion of some of the text.

This next one was interesting, and it involved an actual science experiment. Again, done by a very young kid, the presentation on this one was, well, done by a very young kid (I presume). Note the juxtaposition of the scientific question “Which batteries have more charge AA or AAA?” with the biblical quote “Genesis 1:3 and god said let there be light.”

I didn’t look at this one, “Monument to the Flood” too closely, but I’m guessing that it was about the Noachian deluge. Soil samples and everything. There were a couple of different posters criticizing standard geological models.

This next one is on vestigial organs. I agreed with part of the poster: Vestigial organs are way overblown, and many of them probably aren’t as vestigial as some have suggested. Did you know that in at least one now extinct ancient whale species, the tiny back legs, which might have been thought of as vestigial, are now believed by palaeontologists to have been used to facilitate copulation at sea? Imagine the modeling that went into figuring that one out…

And finally, this one. This is actually where we have an important example of a critique of home schooling. The poster asks “Can Hot Wter Freeze Before Cold?” and using references to various sources and some experimentation, concludes that hot water does freeze before cold. Unfortunately, this is wrong, and the experiments and references indicate fairly common mistakes people make when approaching this issue. Had this work been done in the context of a regular school with a physical science teacher, this student would have been much more likely to have carried out the science correctly.

Just to be clear: Imagine the following experiment. Get a two liter container of water, and divide the water exactly evenly between two identical containers. Heat the water in one up by, say, 30 degrees C (don’t boil it!). Now put both containers in exactly the same sub-freezing environment (like in your freezer … ) and every 10 minutes or so, measure the temperature of both.

What you will find is that the hot water will cool down, initially, at a much faster rate then the cold water, because cooling is dispersal of heat, and the rate of dispersal is proportionate to the differential of the temperature of the water and the surrounding environment. The cold water will also be cooling down, of course. As the hot water cools down, its rate of cooling slows as well.

Eventually, they will both freeze but the cold water will freeze first.

Now, do this experiment. Get two liters of water and put one in one of the containers, and take the other and boil it on the stove. Then put the boiling water in the second container so that the volume of water in both is the same. Now put them both on the counter and leave them until they have reached the same temperature (room temperature). You will find that the water you boiled (then measured) is less in volume than the water you didn’t boil. It was thermally expanded when you measured it. Now put both containers (make sure the temperature is the SAME for both first!) into the freezer, and you will find that less water freezes before more water, all else being equal.

There are other reasons people come to conclude that hot water freezes first. Some people believe that hot water pipes (in their experience) freeze while cold water pipes don’t, in the winter. This may well be true, and has been my personal experience as well. But this is probably because of one of two reasons (I’ve seen both apply): 1) Plumbers (well, do-it-yourselfers, really) pay less attention to insulating hot water pipes because they figure they don’t have to; and 2) over night, as people use the bathroom now and then, say in an apartment building, much more water moves through the cold water pipes than through the hot water pipes, avoiding freezing. It might also be the case that when people leave a faucet dripping to avoid a freeze, they do this with the cold water to save on hot water, and then the hot water pipe freezes.

That is the end of today’s science lesson. I hope you enjoyed it.

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