In this activity, learners discover that it's difficult to distinguish between two different shades of gray when they aren't separated by a boundary. Learners will be surprised when two slightly different shades of the same color look different if there is a sharp boundary between them. But if the boundary is obscured, the two shades appear indistinguishable. Use this activity to help learners explore how the eye-brain system condenses information through a process called lateral inhibition.

This is a short activity for growing the slime mold Physarum polycephalum. It includes materials needed, a three-step procedure, and helpful tips. The site is part of the Turbulent Landscapes exhibit at the Exploratorium. Links to other activities and features of the exhibit are also included.

In this activity about chemistry and electricity, learners form a battery by placing their hands onto plates of different metals. Learners detect the current by reading a DC microammeter attached to the metal plates. Learners experiment with different metals to find out what combination produces the most current as well as testing what happens when they press harder on the plates or wet their hands. Learners also investigate what happens when they wire the plates to a voltmeter.

In this classic hands-on activity, learners estimate the length of a molecule by floating a fatty acid (oleic acid) on water. This lab asks learners to record measurements and make calculations related to volume, diameter, area, and height. Learners also convert meters into nanometers. Includes teacher and student worksheets but lacks in depth procedure information. The author suggests educators search the web for more complete lab instructions.

In this activity, learners will explore globes of frozen water to learn how to ask and then answer 'investigable' questions. The activity includes four short online videos: Introduction, Step-by-Step Demonstration, Going Deeper, and What's Going On. Also available are a concept map and a "Going Further" web page that suggests variations and extensions on this activity.

In this activity, learners investigate the speed of chemical reactions with light sticks. Learners discover that reactions can be sped up or slowed down due to temperature changes.

This activity shows how our experience of the Sun changes with time and location. The sun dagger at Chaco Canyon is thought by many to be a sort of ancient timekeeping device. By creating a place where the movement of the Sun could be tracked day after day, Chacoans could mark the passage of time and gain an idea of when seasons were changing. If the Chacoans could use a particular location and the Sun to tell them about time, can we use time and the Sun to tell us about our location? In this easy experiment, you'll see how the position of the Sun in the sky is related to where we are on the earth.

This is an activity that demonstrates how batteries work using simple household materials. Learners use a pickle, aluminum foil and a pencil to create an electrical circuit that powers a buzzer. Most common batteries--such as car batteries and the batteries inside a flashlight--work on the same principle that the pickle battery works on: two metals suspended in an ion-rich liquid or paste separate an electric charge, creating an electrical current around a circuit. In this activity, the pickle provides the ion-rich liquid - pickles contain salt water, which is rich in ions.

In this activity, learners use gelatin as a lens to investigate the properties of laser light. Learners can view total internal reflection of a beam of light and investigate angles of reflection and refraction. Using different colors of gelatin demonstrates its color filtering properties. Use this activity to help learners explore light reflection and refraction, wavelengths, color, and lenses.

In this activity, learners use a laser pointer and two small rotating mirrors to create a variety of fascinating patterns, which can be easily and dramatically projected on a wall or screen. In this version of the activity, learners use binder clips to build the base of the device. Educators can use a pre-assembled device for demonstration purposes or engage learners in the building process.

In this activity on page 1 of the PDF, learners compare the relative sizes of biological objects (like DNA and bacteria) that can't be seen by the naked eye. Learners will be surprised to discover the range of sizes in the microscopic world. This activity can be followed up with a second activity, "What's in a microbe?", located on page 3 in the same resource.

Light painting is a creative activity that involves creating striking images and illusions using a camera, a light source, and a little practice. Light paintings may be literal representations or impressionistic, color-filled images. When the camera shutter is open (and the room is dark) the film or digital sensor acts like a blank canvas onto which learners "paint" with a flashlight.

The earth’s atmosphere may seem thick when compared to something like your height—but it’s surprisingly thin when compared to the earth’s radius. Here, you can find out exactly how thin, using strips of plastic to model the correctly scaled thickness of the atmosphere on a globe.

Learners use two mirrors to explore how images of images of images can repeat forever. This resource includes a light-ray diagram to help learners understand what they are seeing -- images appear to be grouped in pairs with a front side always facing a front side and a back side always facing a back side. Learners can assist in assembling the Infinity Mirror or use one that has been pre-assembled.

In this activity, learners explore the "nuts and bolts" of gene chips. Learners construct a simple model of a DNA microarray (also known as gene chips) and learn how microarrays can be used to identify and treat disease--including cancer. This resource includes references and an explanation of microarrays.

In this activity about light and perception, learners create pictures in thin air. Using a simple set up of a slide projector, slide, moveable screen or poster board, and a "wand", learners investigate how we see projected images such as those from movies and television. Use this activity to help learners understand concepts associated with light and optics including persistence of vision, reflection, and map projection.

The Ancient Egyptians used a naturally-occurring salt from the banks of the Nile River, called natron, to mummify their dead. Natron is made up primarily of sodium carbonate (a very efficient, but relatively expensive, dehydrating material), with about 17% sodium bicarbonate (baking soda). This activity explains how to create your own fish mummy using common baking soda!

This site dissects a sheep brain to show us the anatomy of memory. See works of an artist who paints entirely from memory. (Compare his paintings to photos of places.) Play interactive games that test your memory -- learn ways to improve it. Discover why some things are easier to remember than others (droodles game). Which facial features help us remember a face? Which image of the penny is correct? Try a mnemonic device called elaborative encoding.

This site shows what blood is, what happens when the immune system goes awry, what are stem cells are, and more. See videos exploring cell structure and function, cell development and motility, plankton, plants, and protozoa. Learn how the sea urchin helps us understand genes, reproduction, and cancer.

To understand how skaters turn in midair, try this little experiment! Individuals can do this activity alone, but it works better with a partner. Used in conjuncture with the rest of the Exploratorium's Skateboard Science website, this activity and others explore the physics of skateboard tricks.