Tuesday, April 22, 2008

Construct a pentagon

This is where mathemagic gets tricky! This is not the only way to construct a pentagon, but I think it is pretty elegant.

I colorcoded the steps - do purple, then blue, then red. I've marked the centers of arcs with x's, and only drawn the arcs instead of the whole circle where I didn't need the whole thing.

This method uses pairs of arcs with equal radii to bisect angles and draw lines at right angles.


For a cool animation of this, check out the wikipedia page:


Saturday, April 19, 2008

Awesome Poster

This poster is beautiful:

It maps the citation relationships between 800,000 scientific papers. Different disciplines are color-coded, so you can find your favorite. At full size, you can even find many sub-specialties labeled.

Full explanation here:

I only wish that they had included some economics papers and the like ... I'd like to see the all-inclusive thought map!

Monday, September 3, 2007

Russian Peasant Multiplication

Check it out: http://www.hunkinsexperiments.com/pages/multiplication.htm

The website is full of fun experiments in cartoon form:

surprise people at work

push a needle through a balloon without popping it.

We used to do the last one at summer science camp, with a slightly different method. All you need is a big balloon (don't inflate it super-tight!) and a wooden skewer dipped in vegetable oil. Then just push it, very slowly, through the balloon. It's easier to go from tip to knot (the long way), at least until you get some practice!Link

Wednesday, August 8, 2007

Get out in the dark! and experiment!

This weekend I had the luck to get out of the city and into the woods -- and one of my favorite things about it, apart from the chance for my brain to escape the internet, was the dark. Real dark. Dark enough to see stars. Dark enough to be afraid of the woods. Not something you can get in the city!

So for your enjoyment, the next time you're out in the dark (or in a closet with nothing else to do) try these mini- experiments. Remember, it can take up to 15 minutes for your eyes to fully adjust to the dark ... so take a walk without a flashlight and get used to it!

1. After your eyes have adjusted outside: pick a star - a pretty faint one. Stare directly at it. Then look a little to the side. Which way is easier to see it?

2. After your eyes have adjusted, get a bright candle or flashlight. Close one eye, gently cover it with your hand, turn on the light, and stare at it with your open eye. Stare for a good 30-60 seconds, then turn off the light and open both eyes. Switch back and forth - what's the difference?

3. Get a bunch of markers or crayons. Write the name of the color with the marker on a paper and save it until the lights come back on. Did you get any right?

The last three experiments have to do with rods and cones in your eyes ... rods are more sensitive, are found more in the periphery of the eye, and only see black and white. Cones see color and they are more concentrated in the center of your eye. So, which ones work in the dark?

Other things to try:

1. Different smells in the dark - use little containers of spices, coffee grounds, lemon juice, vinegar, etc. Or tastes - try different kinds of juice.

2. Sounds in the dark - sit on the ground and close your eyes. Have someone else snap their fingers or tap two spoons together, about 2 feet from your head. Point to where you think the sound is coming from. Try it in different places, then switch. Which is easier to tell apart - left and right, back and forwards, or up and down?

Enjoy! And since I've already done all these, I'd love some new suggestions!

Wednesday, July 11, 2007

Poll: School or Un-School?

I've been thinking about formal education ... I've been a student from pre-school through college, and I've taught kids in elementary schools, camps, college and all kinds of places ... and I have seriously mixed feelings about the system we have now!

So I apologize for the social science tangent, but what did you get out of school?

1. What did you learn in elementary school? high school? college?
2. How much did you enjoy elementary school? high school? college?
3. Is there anything you would have changed to make it more enjoyable or to learn more?
4. What would you have done with your time if you hadn't been in school?

I have a follow-up question, but it's loaded .... I'll save it for later!

Science Underground!

Four proposals, $70 million from a private donor, the former world's largest gold deposit ... and you get an 8 miles deep lab for neutrino science, gravity wave detection, biochemistry, geology, and carbon sequestration! Field trip anyone? Well, we have a few years to plan for it.

NSF Selects Former South Dakota Gold Mine as Deep Underground Science Site

Would you donate money to science? Would you donate your body? Your brain? your time, genes, or house? Let me know! (and no, I'm not taking donations)