In this activity about light and perception, learners discover how a flash of light can create a lingering image called an "afterimage" on the retina of the eye. Learners will be surprised when they continue to see an image of a bright object after staring at it and looking away. Use this activity to introduce learners to principles of optics and perception as well as to explain why the full moon often appears larger when it is on the horizon than when it is overhead. This lesson guide also includes a few extensions like how to take "afterimage photographs."
Exploratorium Science Snacks
Hungry for fresh, exciting science activities based in amazing phenomena? Science Snacks are hands-on, teacher-tested, and use cheap, available materials. Satisfy your curiosity without ever getting full.
All biological cells require the transport of materials across the plasma membrane into and out of the cell. By infusing cubes of agar with a pH indicator, and then soaking the treated cubes in vinegar, you can model how diffusion occurs in cells. Then, by observing cubes of different sizes, you can discover why larger cells might need extra help to transport materials.
Short pieces of chenille stem arranged inside a box look like a random jumble of line segments—until viewed in the proper perspective.
Note: This activity is detail oriented and time intensive. It’s done by threading a long length of fishing line through twenty small holes, and then attaching short pieces of chenille stem to create a suspended pattern. When you look through a viewing hole, that random-looking pattern resolves into the form of a chair. If you think being a watchmaker is something you’d hate, then you might want to rethink doing this Snack!
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."
In this simple exploration, a coiled phone cord slows the motion of a wave so you can see how a single pulse travels and what happens when two traveling wave pulses meet in the middle.
Step outside and discover the diversity of insect life in your neighborhood. Insects are the world’s most diverse group of living things, with over 950,000 identified species and counting. You might think that you’d need to travel to the Amazon to study insects, but they can be found practically everywhere—including right where you happen to be.
This webpage from Exploratorium provides an activity that demonstrates the Bernoulli principle with readily available materials. In this activity a table tennis ball is levitated in a stream of air from a vacuum cleaner. The site provides an explanation of what happens, asks questions about the activity, and also describes applications to flight. This activity is part of Exploratorium's Science Snacks series.
In this quick and simple activity, learners explore how the distribution of the mass of an object determines the position of its center of gravity, its angular momentum, and your ability to balance it. Learners discover it is easier to balance a wooden dowel on the tip of their fingers when a lump of clay is near the top of the stick. Use this activity to introduce learners to rotational inertia.
Hunt for prey and discover the meaning of evolutionary “fitness” in this physically active group game. In this simulation game, teams of predators equipped with genetically different “mouths” (utensils) hunt for “prey” (assorted beans). Over several “generations” of play, the fittest among the predators and prey dominate the population, modeling the evolutionary process of natural selection.
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.
Demonstrate the Bernoulli Principle using simple materials on a small or large scale. This resource includes two activities that allow learners to experience the Bernoulli Principle, in which an object is suspended in air by blowing down on it. Use this activity to explain how atomizers work and why windows are sometimes sucked out of their frames as two trains rush past each other.
In this activity, a spinning bicycle wheel resists efforts to tilt it and point the axle in a new direction. Learners use the bicycle wheel like a giant gyroscope to explore angular momentum and torque. Learners can participate in the assembly of the Bicycle Wheel Gyro or use a preassembled unit to explore these concepts and go for an unexpected spin!
Stare at one color—but see another. You see color when receptor cells (called cones) in your eye’s retina are stimulated by light. There are three types of cones, and each is sensitive to a particular color range. If one or more of the three types of cones adapts to a stimulus because of long exposure, it responds less strongly than it normally would.
The eye’s retina receives and reacts to incoming light and sends signals to the brain, allowing you to see. One part of the retina, however, doesn't give you visual information—this is your eye’s “blind spot.”
This activity provides instructions for using a flashlight and aquarium (or other container of water) to explain why the sky is blue and sunsets are red. When the white light from the sun shines through the earth's atmosphere, it collides with gas molecules with the blue light scattering more than the other colors, leaving a dominant yellow-orange hue to the transmitted light. The scattered light makes the sky blue; the transmitted light makes the sunset reddish orange. The section entitled What's Going On? explains this phenomena.
In this optics activity, learners examine how polarized light can reveal stress patterns in clear plastic. Learners place a fork between two pieces of polarizing material and induce stress by squeezing the tines together. Learners will observe the colored stress pattern in the image of the plastic that is projected onto a screen using an overhead projector. Learners rotate one of the polarizing filters to explore which orientations give the most dramatic color effects. This activity can be related to bones, as bones develop stress patterns from the loads imposed upon them every day.
Here’s a new “spin” on an old toy. In this modern adaptation of a classic toy—the spool racer—a plastic water bottle is propelled by energy stored in a wound-up rubber band.
Watch water boil at room temperature. The temperature at which water boils depends on pressure. You can demonstrate this by dramatically lowering the pressure on a water-filled plastic syringe at room temperature.
Construct a protein through cereal additions. Model the central dogma of molecular biology by constructing a colorful chain using a simple code (and some delicious cereal).
In this activity, learners observe what happens when they give a light source like a neon glow lamp a "Bronx Cheer." The lights appear to wiggle back and forth and flicker when learners blow air through their lips. However, learners will discover that the only thing vibrating is themselves. Use this activity to explore different forms of light as well as visual perception.
In this activity, learners observe as soap bubbles float on a cushion of carbon dioxide gas. Learners blow bubbles into an aquarium filled with a slab of dry ice. Learners will be amazed as the bubbles hover on the denser layer of carbon dioxide gas, then begin to expand and sink before freezing on the dry ice. Use this activity to discuss sublimation, density, and osmosis as well as principles of buoyancy, semipermeability, and interference.
Create giant bubbles! Bubbles are fascinating. What gives them their shape? What makes them break or last? What causes the colors and patterns in the soap film, and why do they change?
Turn an old CD into a spectroscope to analyze light—you may be surprised by what you see. Try pointing your CD spectroscope at the fluorescent light in your room, sunlit clouds in the sky, even your friend’s colored shirt to reveal the wavelengths of light that mix together to create the color you see!
Use your cell phone to explore the mini-scopic world. Open your eyes to the amazing world of the ultra-tiny when you convert your cell phone into a portable, picture-taking Miniscope using a simple plastic lens from a laser pointer.
Every cell in your body needs to take in nutrients, oxygen, and raw materials and export wastes and other substances—but it’s not just a random traffic jam! A cell membrane (also called a plasma membrane) regulates what comes in and what goes out. Explore the properties of soap films and relate them to the properties of plasma membranes and the mechanics of transport across membranes.
In this activity about electricity, learners produce a spark that they can feel, see, and hear. Learners rub a Styrofoam plate with wool to give it an electric charge. Then, they use the charged Styrofoam to charge an aluminum pie pan. Essentially, learners build an electrophorus (Greek for "charge carrier"). This resource also contains instructions on how to build a large charge carrier called a "Leyden Jar" using a plastic film can.
In this activity related to magnetism and electricity, learners create a magnetic field that's stronger than the Earth's magnetic field. Learners use electric currents that are stronger than the field of the Earth to move a compass needle. The assembly is made using a lantern battery, heavy wire, a Tinkertoyă˘ set, and poster board and utilizes 4-6 small compasses and 2 electrical lead wires.
In this optics activity, learners discover that not all shadows are black. Learners explore human color perception by using colored lights to make additive color mixtures. With three colored lights, learners can make shadows of seven different colors. They can also explore how to make shadows of individual colors, including black. Use this activity demonstrate how receptors in the retina of the eye work to see color.
In this activity, learners make their own heat waves in an aquarium. Warmer water rising through cooler water creates turbulence effects that bend light, allowing you to project swirling shadows onto a screen. Use this demonstration to show convection currents in water as well as light refraction in a simple, visually appealing way.
The phenomenon is thermal expansion of copper. This demonstration allows an observer to see the effect of heating (and cooling) a copper tube. When heated, the copper tube lengthens and thickens. When cooled, the tube shrinks. The lengthening of the rod rotates a toothpick with an attached flag to make the expansion visible and measurable.
In this optics/mathematics activity, learners use two hinged mirrors to create a kaleidoscope that shows multiple images of an object. Learners discover that the number of images reflected in the mirrors depends on the angle between the mirrors. Learners also observe that when they set the hinged mirrors on top of a third mirror, they create a reflector that always sends light back in the direction from which it came. Use this activity to introduce basic principles of light and optics including angle of reflection and angle of incidence.
In this optics activity, demonstrate diffraction using a candle or a small bright flashlight bulb and a slide made with two pencils. Learners will observe the diffraction pattern and learn that light has wavelike properties.
This activity from the Exploratorium provides an introduction to the diffraction of light which indicates its wavelike properties. Two pencils are used to create a slit through which a flashlight bulb or candle˘ďď_s light is examined. The site contains an explanation of the observed interference patterns, additional materials that can be experimented with, and an extension activity. This activity is part of Exploratorium's Science Snacks series.
The Drawing Board consists of a marking pen that remains stationary and a platform that swings beneath the pen, acting as a pendulum. As the platform swings, the pen marks a sheet of paper that is fastened to the platform, generating beautiful repetitive patterns. These colorful designs contain hidden lessons in physics. This resource includes instructions for making a large-scale Drawing Board as well.
In this activity related to magnetism and electricity, learners discover that a magnet falls more slowly through a metallic tube than it does through a nonmetallic tube. Use this activity to illustrate how eddy currents in an electrical conductor create a magnetic field that exerts an opposing force on the falling magnet, which makes it fall at a slower rate. This activity guide also includes demonstration instructions involving two thick, flat pieces of aluminum to illustrate the same principle.
In this activity about electricity, learners explore how static electricity can make electric "fleas" jump up and down. Learners use a piece of wool cloth or fur to charge a sheet of acrylic plastic. Then, they observe as tiny bits of Styrofoam, spices, ceiling glitter, or rice (aka "fleas") jump up to the plastic and then back down.
This activity from the Exploratorium provides instructions to build an electroscope, a device that detects electrical charge. Common, inexpensive materials including film canisters, 3-M Scotch Magic™ Tape, and a plastic comb are used to show the attractions and repulsions between positively and negatively charged objects. The site also provides an explanation of the results and suggestions for extension activities.
In this fun optics activity, learners explore principles of light, reflection (mirrors), and perception. Learners work in pairs and sit on opposite sides of a "two-way" mirror. Both partners vary the amount light illuminating their faces. As they adjust the light, they begin to see themselves gradually assuming aspects of their partner's features, so that their image becomes a "composite" person. This activate guide includes instructions on how to build a two-way mirror.
In this weather-related activity, learners make a portable cloud in a bottle. Learners discover that clouds form when invisible water vapor in the air is cooled enough to form tiny droplets of liquid water. You an accomplish the same cooling effect by rapidly expanding air in a jar using a wide-mouth jar, rubber glove, matches, and tap water. This activity can be conducted as a demonstration or by learners with adult supervision.
This highly visual model demonstrates the atomic theory of matter which states that a gas is made up of tiny particles of atoms that are in constant motion, smashing into each other. Balls, representing molecules, move within a cage container to simulate this phenomenon. A hair dryer provides the heat to simulate the heating and cooling of gas: the faster the balls are moving, the hotter the gas. Learners observe how the balls move at a slower rate at lower "temperatures."
In this activity about light and refraction, learners discover how a lens creates an image that hangs in midair. A large Fresnel lens creates upside-down images of distant objects and right-side-up images of nearby objects. Learners can locate the upside-down images by using a piece of white paper as a screen. The right-side-up images are harder to find. Activity includes detailed explanations and diagrams to explain how the images are created.
In this activity, learners explore liquid crystals, light and temperature. Using a postcard made of temperature-sensitive liquid crystal material, learners monitor temperature changes. By observing these changes, learners show that dark materials absorb and reemit the energy contained in light more readily than light-colored materials. Learners can also distinguish energy absorbed and reemited by radiation, convection, and conduction by comparing the behavior of black, white, and silver objects. This resource guide includes detailed explanation of the phenomenon and background information about liquid crystals.
In this activity, learners explore why the sky is blue. Learners model the scattering of light by the atmosphere, which creates the blue sky and red sunset, using a flashlight and clear glue sticks. This resource guide includes an explanation of how light scatters and how this scattering can cause the polarization of light.
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.
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 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.
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 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.
In this activity and demonstration about electricity and magnetism, learners observe how the current generated when one copper coil swings through a magnetic field starts a second coil swinging. Learners also explore what happens when they change the polarity of the magnet, reverse the coil, or add a clip lead to short-circuit the coils. Use this activity to illustrate how electricity and magnetism interact. The assembly of the electromagnetic swing device takes about an hour.
In this activity about electricity and magnetism, learners discover how a doorbell works. A coil of wire with current flowing through it forms an electromagnet that acts similar to a bar magnet. The coil will magnetize an iron nail and attract it in a remarkably vigorous way.
In this activity about light and reflection, learners discover that what you see is often affected by what you expect to see. Learners hold on to a device consisting of two mirrors glued back to back to each other with a dowel handle on either side. While looking at one side of the mirror, learners move one hand on the other side of the mirror. They will be surprised as their brain is fooled into thinking that the image it sees in the mirror is actually their other hand. Learners can participate in assembling the mirror device or use a pre-assembled one. This resource also includes a simpler version of this activity in the "etcetera" section at the bottom of the guide.
In this activity about light and perception, learners create and observe moire patterns. These special patterns, which appear when two repetitive patterns overlap, can also be used to help learners understand wave interference. Learners will use various objects including pocket combs, window screens, and transparencies to investigate moire patterns in different ways.
In this activity about electricity and magnetism, learners examine what happens when a magnet exerts a force on a current-carrying wire. Using a simple device, learners discover that when an electrical current flows through a magnetic field, a force is exerted on the current and this force can be used to make an electric motor. Learners will experiment to find out what happens when they reverse the direction of current flow. They will also discover a mathematical tool called the "right-hand rule."