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Gallium is a silvery metal with atomic number 31. It’s used in semiconductors and LEDs, but the cool thing about it is its melting point, which is only about 85 degrees Fahrenheit. If you hold a solid gallium crystal in your hand, your body heat will cause it to slowly melt into a silvery metallic puddle. Pour it into a dish, and it freezes back into a solid.

While you probably shouldn’t lick your fingers after playing with it, gallium isn’t toxic and won’t make you crazy like mercury does. And if you get tired of it, you can melt it onto glass and make yourself a mirror.

Price: $80

Someone get me this for my non-birthday. 


Should Students Use Wikipedia?

  • Imagine the following fake conversation with a student:

Student: The instructor in another course said something about antimatter. What is antimatter? Where could I read about that?

Me: Well, you could go to Wikipedia. I am sure the page on anti-matter has a nice summary.

Student: Wikipedia??? Really? I thought all faculty hated Wikipedia. We were told it’s not a good thing to use.

Interesting. What do faculty think about students using Wikipedia? I have this unjustified feeling that it is a fairly straightforward source for basic information. Let me take a look at a few pages:

Looking at this sample, how accurate are these pages? The antimatter page seems to have a good summary of the topic with no obvious errors.

Apparently, there isn’t a Wikipedia page on the Momentum Principle. I thought that was odd. Well, the page on Impulse (physics) seems to be essentially the same as the momentum principle. It isn’t exactly what I would write, but it isn’t wrong either. Of course, I could probably say the same complaint about many of the physics textbooks. Finally, the Rhett Allain page is brief — but again not wrong.

Is Wikipedia evil? I don’t think so. Wikipedia is a tool, just like a lot of other things. It can be abused or it can be used for the good of mankind. Really, it isn’t much different than the information you would find in a textbook. Perhaps in the early days of Wikipedia, there was some unreliable stuff in there. However, I think that Wikipedia has matured enough that you won’t find too many seriously wrong things in there. You still find incorrect things in textbooks, so … not much different.

Then can students use Wikipedia? I think the problem some faculty have is that they don’t want students to use Wikipedia because it makes the assignment too easy. My feeling on this is that perhaps there should be a different assignment. Really, it depends on the learning goals. If the goal is to process and synthesize information, I think Wikipedia should be included in that process. If the goal is to learn how to find things in a library, then clearly Wikipedia shouldn’t be used.

Wikipedia is like a calculator in math classes. What if there was a math assignment where students were to do long division? Would it be wrong for the students to use a calculator? I think it depends. Why are they doing long division? In the past, long division was taught in schools so that students could divide numbers. But if the goal is to divide stuff, a calculator would make more sense.

There is another reason to teach long division: to give insight into how division works and what place value means. If this is the goal, the calculator actually doesn’t help. It just skips the whole processes, so it would be a bad-thing.

I need to make another post about long division. You know what is cool about long division? Doing long division with binary numbers.

(Source: Wired)

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