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Showing posts from October, 2014

Propeller Powered Balloon Helicopters

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For today's Curiosity Machine classes, our last meeting of the four-week session, we did an exciting project from the Curiosity Machine website: balloon helicopters! We learned about different kinds of energy, particularly elastic potential energy. Elastic potential energy is the potential energy stored when you bend, stretch or deform an object, and that energy converts to kinetic energy as the object bounces back. Here's a great website that explains it pretty well: Physics 20 Project. We discussed examples of elastic potential energy using a Family Feud presentation I made on Scratch. You can click on the image below to see the project, though it's supposed to be used as a tool for discussion: The project itself was challenging and I'm glad I worked on my sample ahead of time. But it's so exciting to see those balloons fly! First, you have to cut a boba straw to about the same length as the rubber band you plan to use (when it's at equilibrium). Usi…

Octopus Chromatophores

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Today we learned about color changing animals and how they're able to expand or contract special pigment sacs called chromatophores in their skin, in order to give the overall visual effect of having changed color. In reality, they have just chosen which pigments to expand and which ones to shrink, but all the pigments are there! We talked about how octopuses do this and how they also have papillae in their skin that can change the texture of their skin from smooth to rough or bumpy, which gives them an added camouflage benefit. To demonstrate how this works, I programmed a simulation of chromatophores expanding and contracting to match their environment using Scratch. You just click on the words Brown, Red, or Yellow to make the background change, and watch as the chromatophores change by expanding or contracting to emphasize that color! Click on the picture to go to the Scratch website and play with this simulation. Our hands on project today was pretty easy--to build a chr…

Wind Pumps

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Today's project was designing a wind-powered water pump!


We discussed the history of harnessing the wind to power machines, from Hero of Alexandria's wind-powered pipe organ in the 1st century A.D. to the wind pumps used in Muslim cultures in the Middle East and Central Asia, to the windmills created by the Dutch (which--I didn't know before--could mill grain AND pump water from the ground!).

The book I mentioned in our discussion today was called Wind Power, written by Ian Graham and published by Raintree Steck-Vaughn Publishers.

We talked about Daniel Halladay, the American inventor of the wind pumps used in farms across America. We talked about the Law of Conservation of Energy, how energy is never created or destroyed, but only changes form--in this case, changing from kinetic energy to mechanical energy, and in wind turbines that power homes, it is also converted to electrical energy.

We talked about converting different kinds of motion using a machine cal…

Suspension Bridges

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We've started up Curiosity Machine again! For yesterday's Curiosity Machine classes, we built suspension bridges! This is one of the civil engineering challenges on Curiositymachine.org. First we learned how spiders build their webs:

https://www.youtube.com/watch?v=9qaaYlpVmJM

This picture from p. 21 of Do All Spiders Spin Webs? by Melvin and Gilda Berger, Illustrated by Roberto Osti and published by Scholastic illustrates the process of a spider web very well: Then we learned about the basics of suspension bridge design, how the cables help a bridge to hold firm and strong and balance out all the forces acting on it in all directions. I showed the kids this page from the book Bridges! Amazing Structures to Design, Build & Test by Carol A. Johmann and Elizabeth J. Rieth, published by Williamson Publishing: We learned about John Roebling, the great engineer behind the Brooklyn Bridge, and how he also strengthened the Niagra Bridge with more trusses and stays. A…