In this activity, learners use a hand-made protractor to measure angles they find in playground equipment. Learners will observe that angle measurements do not change with distance, because they are distance invariant, or constant. Note: The "Pocket Protractor" activity should be done ahead as a separate activity (see related resource), but a standard protractor can be used as a substitute.

In this demonstration, amaze learners by performing simple tricks using mirrors. These tricks take advantage of how a mirror can reflect your right side so it appears to be your left side. To make the effect more dramatic, cover the mirror with a cloth, climb onto the table, straddle the mirror, and then drop the cloth as you appear to "take off." This resource contains information about how this trick was applied during the making of the movie "Star Wars."

This trick from Exploratorium physicist Paul Doherty lets you add together the bounces of two balls and send one ball flying. When we tried this trick on the Exploratorium's exhibit floor, we gathered a crowd of visitors who wanted to know what we were doing. We explained that we were engaged in serious scientific experimentation related to energy transfer. Some of them may have believed us. If you'd like to go into the physical calculations of this phenomenam, see the related resource "Bouncing Balls" - it's the same activity but with the math explained.

In this optics activity, learners discover that when they rotate a special black and white pattern called a Benham's Disk, it produces the illusion of colored rings. Learners experiment with the speed of rotation and direction of rotation to observe varying patterns. Use this activity to explain to learners how our eyes detect color and how different color receptors in the eye respond at different rates.

In this math activity, learners observe and sketch cracking patterns in pavement. Learners use a protractor to measure and label the angles of their sketches and conclude if some angles are more common than others.

In this activity, learners create angle-measuring devices--protractors--out of paper. Learners follow a series of steps to fold a square sheet of paper into a triangular Pocket Protractor. Learners will practice measuring and identifying the angles of a triangle.

In this activity, learners create angle-measuring devices--protractors--out of paper. Learners follow a series of steps to fold a square sheet of paper into a triangular Pocket Protractor. Learners will practice measuring and identifying the angles of a triangle.

In this activity, learners make a stroboscope--a spinning disk with slits around the edge that you look through. Brief but frequent glimpses of images seen through the slits lead to a surprising result, which teaches learners about vision and the human nervous system. The activity includes three short online videos: Introduction, Step-by-Step Instructions, and What's Going On. Also available: a concept map and a "Going Further" document that suggests variations on this activity.