The Topic: 

Easier - Light is brightness that comes from an object such as the sun, a fire, a flashlight, or a lamp.
Harder - All light comes from atoms. Atoms that produce light have either gained energy by absorbing light from another source or by being struck by other particles. It is this 'extra energy' that causes an atom to give off light. The light being emitted is carrying off the extra energy.
Our light comes from the sun. Light from the sun also heats our earth. Sunlight causes plant growth; the sun's energy is stored in the plants. Ancient plant life has provided the earth's supply of fossil fuels; the coal, natural gas, and oil deposits.
Light has been described as a wave because the movement of light was seen as being similar to an ocean wave. However more recent theory sees light as a small particle, called a photon. A photon moves in a straight line. In both the light wave and photon descriptions, the light has energy. Is light a wave or a particle? It is strictly neither; however sometimes it acts like a wave and other times it is more like a particle. It is called an electromagnetic wave. The amount of energy that is carried by the wave or photon largely determines its color.
Circles of Light: The Mathematics of Rainbows at the University of Minnesota
How are rainbows formed? Why do they only occur when the sun is behind the observer? If the sun is low on the horizon, at what angle in the sky should we expect to see a rainbow?
Make a Splash with Color from the Tech Museum
This exhibit has three main sections: Talking about Color, The Lighter Side of Color, and An Eye on Color. Explore the relationship of light and color.
Other Color and Light Sites:
2)Color Perception
3) Seeing Color (Arizona State University)
Optics for Kids: Science and Engineering by Bruce Irving (Optical Research Associates)
This site provides a look at some optical basics.
Physics of Light at Physics4Kids
Visit here to learn a little about light and it's connection to everything in the Universe.
After exploring several of the websites, complete one or more of the following activities on light.
Draw a Picture of a Rainbow. Create your own rainbow. It can be realistic or a rainbow that you would like to see.
Write a Poem About Light. If you want more information about poetry, visit the Poetry for Kids website. Then write a poem about light. You may even want to illustrate your finished poem.
Complete a Light WebQuest. Follow or adapt the directions found at one of these webQuest activities: 
1) Light and Its Properties by Patti Fontenot (Grade 7-9)
2) Light Up Your Life (Grade 5)
Imagine a World Without Light! Think about the possibility of a planet without light. Sight as we know it would not be possible. Food and oxygen would not be produced. But on your pretend planet, somehow life has adapted. Imagine that it is so and write a 'science fiction' story about your world without light.
Complete Some Light & Solar Experiments. Follow the procedures found these sites. 
1) Seeing the Invisible
2) Dracula's Library at The Atoms Family (Grade 5-12)
3) What Stores Solar Energy Best?
4) Make A Pizza Box Solar Oven
Websites By Kids For Kids
Discovering Light (1999 ThinkQuest Project)
This site will lead you into the phenomena, properties, and applications of light.
Exciting World of Light and Energy (1998 ThinkQuest Project)
Did you know that a rainbow is formed by light refracted (or bent) through drops of water in the air?
Fiat Lux (Let There be Light) 1999 ThinkQuest Project
Learn about the way that light moves through space, time, and how light is seen by the eye, how the image is transmitted to the brain, and how the brain interprets the image.
Light (1999 Thinkquest Junior Project)
Here you can learn about: the sun, moon, light waves, colors,and projects that you can do.
Light (1999 ThinkQuest Project)
This site will teach you all about lasers, wavelengths, mirrors, diffraction, reflection, and other cool properties of light.
Light, Color & Optics at New Trier Connections Project
As the website title says, the projects here deal with properties of light, color and optics.
Related Site:
2) Reflection
The Light (1998 ThinkQuest Project)
You may think of light only in terms of its physical, biological, and chemical properties, but it is also a religious symbol, is important in artistic expression, and even affects our feelings. You can learn about everything from the aurora borealis to how blind kids experience light and color.
Light & Energy (Part of the Wizard's Lab, a 1997 ThinkQuest Project)
Light has a relationship to energy and vice-versa.
Photography | The Art of Light (1999 ThinkQuest Project)
The major contribution of the site is the clear explanation of light: the most important element in photography.
See The Light (1997 ThinkQuest Project)
This site will enlighten you about everything from the speed to light to color, reflection, and mirrors.
More Websites For Light
Arizona Solar Center
Come inside and explore various solar technologies, including photovoltaics, solar cooking, solar water heating, and passive solar architecture.
Other Solar Energy Websites:
2) Roofus' Solar and Efficient Neighborhood
3) Schools Going Solar
Dynamic Sun at Space Science Institute
Here you learn about the source of light, solar flares, corona, and much more.
Exposure Explained
In order for an image to be captured on film, it must be exposed to light. Explore the relationship between photography and light.
Light Fantastic at Thinking Fountain
Have some fun with a few light activities!
Light and Optics
(Department of Atmospheric Sciences (DAS), Univ. of Illinois at Urbana-Champaign)
As sunlight (or moonlight) enters the atmosphere, it is either absorbed, reflected, scattered, refracted or diffracted by atmospheric particles or air molecules. These processes, individually or in combination, are responsible for producing most optical effects.
Lighting Resource
This links-page connects to a ton of websites on artificial lighting.
Snacks about Light at The Exploratorium
Here are lots of activity 'snacks' for you to do.
Similar Website:
2) Snacks about Perception
Star Light Star Bright
Make some waves and explore the energy connection. Find out how hot a star is just by looking at it!
Wave Properties of Light at the University of Winnipeg
Learn more about the general properties of light and waves.
Websites for Teachers
Color & Light--Teacher Resources (TrackStar)
Here you find resources for teaching lessons about color, the spectrum, shadows, heat, refraction, reflection, and light.
The Color of Light at The Franklin Institute Online (Grade 4-6)
Ask your students what color they think light is. A silly question? Sunlight or light from a lamp may look "white" but it is really made up of different colors.
Related Lessons:
2) Adding Colors
3) The All-American Afterimage
Direct and Diffuse Light at the University of Illinois
This lesson helps the learner understand the difference between direct and diffuse light.
Related Lessons:
2) Light and Heat
3) Reflectivity and Absorption
Light Lesson
What affect does water have on light? Why is water blue? This set of explorations should help you get a better understanding of seeing in the underwater world.
Investigating Optics (Grade 8
Three lessons on Optics
Science Activities for Light
The following activities involve hands-on experimentation with light ideas. Links to activities form Nye Labs, the Exploratorium, and Newton's Apple.
Shadow Pictures at KinderArt (Grade 3-8)
This activity teaches students about light, shade, and shadow.
Solar Matters (Grade 4-8)
This unit contains exercises using free or low-cost materials that give students hands-on experience with the principles of solar water heating, photovoltaics, solar cooking and other subjects.
light wave
speed of light
electromagnetic radiation
white light
optical illusion
visible spectrum
gamma ray
magnifying glass
solar energy
transverse wave
sun safety
Created by Annette Lamb and Larry Johnson, 1/99, Updated4/00. Update Nancy Smith 10/02