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.

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.

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.

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.

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.

This is an online exhibit about color perception. Learners set a random background color and then try to mix red, blue, and green light to match. Although this is a perception activity, it also demonstrates the difference between mixing colors of light and mixing pigments. Why when mixing pigments does the color darken? How does this differ from mixing colored light? Find out here!

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 two-part activity, learners use everyday materials to visualize one mole of gas or 22.4 liters of gas. The first activity involves sublimating dry ice in large garbage bag. The second activity uses plastic bottles.

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."

Lets us look over the shoulders of scientists and glimpse the often-unseen moments of investigation. Take virtual field trips to eight observatories -- Arecibo, where astrobiologists search for signs of life beyond the solar system; Las Cuevas, a research station in Central America's largest remaining rainforest; and others. See interviews, photos, and broadcasts that explore the origins of matter, the universe, and life itself.

In this activity, learners build bridges using paper and explore how much weight each bridge design can support. There is an element of surprise, which increases learners' interest in the physics, when they discover just how strong they can make this seemingly flimsy material. This lesson guide includes background information, discussion questions, demonstration ideas and extensions.

In this activity, learners explore the question "What is paper?" Learners discover the processes and materials required to make paper while experimenting with different recycled fibers and tools.

In this activity about light and reflection, learners use a special device called a Mirage Maker䋢 to create an illusion. What they perceive as an object is really an image in space, created by two concave mirrors. Learners will be surprised when they try to grab the object on the mirror and there's nothing there! Activity includes a light-ray diagram to help explain how the image is created.

In this activity, students observe fluid motion and the formation of convection cells as a solution of soap and water is heated. This procedure can be performed as a demonstration by the teacher, or older students can conduct the experiment themselves. A list of materials, instructions, and a description of the convective process are included.

In this activity, learners construct a device out of a piezoelectric igniter, like those used as barbecue lighters. Learners use the device to remotely start current flowing in a simple series circuit containing a small electric fan.