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displaying 11 - 20 of 52 lessons
title description rating updated author
Positive Afterimages

This lesson contains a short explanation of positive afterimages and some suggestions on how best to see them.

When light shines on the retina, chemical and electrical signals are sent to the brain, providing the basis for our sense of vision. When the light is turned...

Average: 4 (20 votes)
8-Jun-2016 guy
Motion-induced Blindness Illusions

Motion induced blindness illusions use apparent background motion to make static portions of the visual field temporarily disappear from view. They produce an effect that seems similar to the blind spot in the eye, or the disappearance of images in Cheshire cat illusions,...

Average: 3.4 (90 votes)
25-May-2016 guy motion blindness illusion
Anatomy of the Eye

This lesson provides an overview of the anatomy of the eye and suggests several simple activites for exploration, including

  • observing pupil response to variations in light
  • verifying the inverted image on the retina
  • comparing central and peripheral...
Average: 3.8 (4 votes)
25-May-2016 guy diagram of eye
Lilac Chaser Illusion

The Lilac Chaser illusion is a creation by Jeremy Hinton that relates to the effects of desensitization (and afterimages), motion-induced blindness, and beta movement (perceiving motion from static images). It makes a great follow-up activity after a lesson on negative...

Average: 3.8 (19 votes)
25-May-2016 guy Lila Chaser
Smoke Ring Machines and Dolphin Bubbles

Smoke rings offer wonderful lessons in fluid dynamics. Use them to initiate discussions on fluid flow, air pressure, and Bernoulli's principle. This lesson contains instructions for how to build your own smoke ring machine out of an empty soda bottle, and outlines the...

Average: 4 (10 votes)
25-May-2016 guy vortex chamber
Minimalist Motors


Building a simple motor is much easier than most people realize. All it takes is a battery, a magnet and a piece of wire. This lesson reviews some simple motors and demonstrates a minimalist design constructed from a button cell battery, some wire, and a small but...

Average: 4 (5 votes)
7-Jan-2016 guy
Pendulum Waves

This lesson outlines the construction and operation of a pendulum wave machine that can be built from inexpensive materials in the classroom. Building the demonstration requires a fair amount of patience: construction only takes about 30 minutes, but adjustments and fine...

Average: 4.4 (32 votes)
7-Jan-2016 guy Pendulum Wave
Measuring the Density of Pennies

This activity provides a detailed lesson in measurement and measurement errors, which can be adapted to many different age groups, starting with any group that knows a little bit of geometry (specifically, how to calculate the volume of a disk). The focus of the lesson is on...

Average: 3.5 (40 votes)
7-Jan-2016 guy magnified penny
Upside-down Water

Turn a glass of water upside down without letting the water fall out. The secret to this trick involves some basic lessons in air pressure. Best performed over a teacher's head.

Average: 4.3 (174 votes)
3-Jan-2016 guy forces on the upside-down water glass
Tabletop Flaming Hurricane

This experiment demonstrates the basic features of hurricanes and tornadoes in spectacular fashion. With a kitchen turntable or a spinning stool, it can be put together with common classroom materials. A tutorial on hurricanes is included. Lecture slides are attached.

Average: 4.5 (4 votes)
3-Jan-2016 guy flaming vortex