Be able to design and construct a mechanism (in this case, an anemometer) based on a basic description and an understanding of the principles and design goals of the mechanism.
What is the assumed knowledge?
Basic knowledge of electricity (electric current, basic circuit concepts)
Basic understanding of electric motors (understanding of motor .> generator concept)
Concrete Deliverable
Have people create an anemometer out of found materials (or in case of Edgerton, bag-o-stuff: in either case, DESIGN) that they can calibrate to find out the speed of the wind.
Lesson Structure
Introduction
Big picture Windmills! What do they do, and why are they useful? (if part of a larger curriculum, perhaps mention something along the lines of .In X lessons, we are going to build a working windmill of our own. But to know what sort of windmill we need to build we need to measure the speed of the wind; so we.re going to build our own anemometers to do it)
Motors They create torque if given electrical power, but also can be run backwards to GENERATE power.
Class Demo Show the motor. This is a motor! What happens when we plug the motor into a battery? (Use a prop motor. The motor should be a small DC, attached to some sort of wheel that can both visibly spin and provide enough grip to turn. It should have wires that can be easily attached and detached to things (perhaps crocodile clips) so that it can quickly attach to both a battery/power supply and an LED). Plug the motor into a battery, demonstrate it turning a wheel.
What is happening inside the motor to make that happen?
Review of electric current from battery (this is assumed knowledge)
Coils, magnets (perhaps a demo coil-and-magnet to light an LED? magnet flashlight from previous lesson?)
Motor is essentially lots of these bunched together.
How can we use the motors to measure the wind?
Front of class demo: lights attached to motor get brighter if motor is turned faster.
Group demo: Each group has a motor and a voltmeter. Attach the motor to the voltmeter, and get students to take turns turning the handle to see what voltage they can produce. (If this is going to be a competition, probably safer to use something like how close can you get to 3v rather than .how many volts can you get??.)
So, if the voltage is related to how fast the motor is being turned - if we get the wind to turn the motor, we can figure out the speed of the wind.
ANEMOMETERS!
Front of class DESCRIPTION of anemometer, using board or example materials. DO NOT BUILD AND SHOW COMPLETE ANEMOMETER. Examples should be descriptive, not prescriptive - for instance, to show the wind-catching cup principle, fold a piece of paper and show how it catches the wind (like this, but with a stronger material).
At this point, either:
If the class has bags-o-stuff, hand them out and let students draw, do some designs, test new things. Have a fan on in the room so wind-catching properties can be tested.
If the class is working with found materials either:
before this lesson, they were assigned to find things to bring, OR
(preferable) Allow a few minutes for discussion within groups about materials that would be good for anemometer-building. Then this half of the lesson ends, and students are asked to come to the next lesson with things with which to build their anemometer.
Anemometer building!
Building should be done in pairs.
Teachers go around teams, give help when needed but allow students to design their own anemometer.