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!

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!

Construct a perfect square

Geometry and Mathemagic

I recently took up drawing and painting, so I'm learning to see the world around me as shapes and forms, colors and lines. This reminds me of a book I once read: A Beginners Guide to Constructing the Universe: The Mathematical Archetypes of Nature, Art, and Science, by Michael Schneider. In it, the author shows you how to construct perfect geometrical shapes, from a triangle to a decagon, using only a compass and a straightedge. He also discusses (and illustrates!) the roles these shapes, and the numbers 1-10 play in art, architecture, and nature.

I don't have the book in front of me, but I recall that you can make each shape, from 3 sides to 12 sides, except 7 and 11. I'm going to give it a try (using Illustrator instead of paper) and show you here if I can figure it out.

Triangle is the easiest of course. Three circles of the same size, with the edge of each one aligned with the centers of the others, gives you an equilateral triangle. If you want to try this, or other shapes, with a pencil and paper, here are the rules:

1. You can make circles and straight lines.
2. You can mark the centers of circles, the points where lines cross, and the point where a line is tangent to a circle.
3. You can use the compass to mark off distances.
4. You may not measure distances with a ruler, or angles with anything.

Go to it! I'll post my attempts as soon I complete them.

Also, if there are any mathematical minds out there, I've been wondering if there is a way to test which shapes can and cannot be drawn by this method. For example, why not seven sides? Is there a formula to tell you which would work?

- lily