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displaying 21 - 30 of 52 lessons
title description rating updated author
Seeing Blood Vessels in the Eye

Describes a technique for seeing the shadows of blood vessels in your eye. Provides a great opportunity for discussing the anatomy of the eye. Requires a dark place.

For more examples of optical illusions caused by visual desensitization, check out our summary...

Average: 3.8 (4 votes)
3-Jun-2015 guy retina shadows
Cheshire Cat Illusions

Cheshire cat illusions are images that fade slowly away as you stare at them. They result from desensitization in the eye (and brain) when you view them without moving your eyes. This lesson explains the mechanism behind the disappearance, and provides several examples of...

Average: 3.8 (5 votes)
3-Jun-2015 guy Cheshire cat
Yang and Yin - negative afterimages

This lesson provides a tutorial on the mechanism behind negative afterimages, and includes three afterimage illusions for demonstration. Lecture slides are attached with all images.

For more examples of optical illusions caused by visual desensitization, check out our...

Average: 3.7 (3 votes)
3-Jun-2015 guy Mona Lisa negative
Bernoulli's Beach Ball

This lesson describes how to float a beach ball on a stream of air. The exercise makes for a magical demonstration in front of a large audience or a lot of fun in an office full of paper. Use it to teach the concept of Bernoulli's principle, which describes the relation...

Average: 4 (4 votes)
3-Jun-2015 guy
Bernoulli's Balloon

Bernoulli's principle states that a region of fast moving fluid exerts less pressure on its surroundings than a region of slow moving fluid. This principle explains a clever trick for blowing up a long thin balloon in a single breath. Stage a friendly competition in class...

Average: 4.2 (5 votes)
3-Jun-2015 guy Bernoulli mouth
Vortex in a Bottle

Instructions for building the vortex in a bottle, a device that produces a vortex like the one found in a bathtub drain. The device is completely self-contained and can be used in any classroom setting. It is simple enough and cheap enough for students to build their own to...

Average: 4.7 (3 votes)
31-May-2015 guy vortex in a bottle
Desk Chair Angular Momentum

Describes a simple demonstration of angular momentum conservation using a spinning desk chair. A short tutorial of angular momentum and angular momentum conservation is included.

Average: 4.5 (2 votes)
28-May-2015 guy
A Floating Compass

This lesson provides

  • plans for making a simple compass and
  • tips on magnetizing a needle

learning goals:

  • understand the mechanism behind magnetization
  • figure out which way is north

For other ideas and more in-depth...

Average: 3 (1 vote)
22-May-2015 guy
Earth's Magnetic Field

This lesson gives some information on Earth's magnetic field: the physics of how it is produced and its geologic history. Many suggestions for further reading are also listed. It might be considered useful background for any activity having to do with magnetic compasses....

Average: 5 (3 votes)
22-May-2015 guy history of the north magnetic pole
Diamagnetism - Levitating Graphite and Frogs

Diamagnetic materials are repelled by a magnet, in contrast to magnetic materials (like iron), which are attracted to a magnet. This lesson describes several demonstrations of diamagnetic repulsion using water and graphite (both diamagnets), with inexpensive setups. The most...

Average: 3 (3 votes)
22-May-2015 guy Pyrolitic graphite levitation