Light: What Is It and How Does It Work? Lesson One

 What everyday objects can you think of that are able to emit light? Light Is All Around Us

 Now, try and find some of these objects in our classroom Light Is All Around Us

 Consider the following scenario:  The world no longer has any of the manmade objects that give us light.  Where do we get light from?  How do we live?  Share some of your thoughts with your neighbor and then we will find out what the rest of the class thinks Light Is All Around Us… Oh Wait, No It Isn’t

 Try to come up with a definition for light in your own words What Does Light Even Mean?

 Here’s a definition for light: What Does Light Even Mean? Light is the form of radiant energy that stimulates the organs of sight, having for normal human vision wavelengths ranging from about 3900 to 7700 angstroms and traveling at a speed of about km per second. One angstrom = cm. Wait, what? Maybe I should have simplified that. Let’s try a definition without all of those strange science terms.

 Here’s our new definition for light: What Does Light Even Mean? Light is a type of energy we can see. Much better!

 There are some other things that you should know about light and we refer to them as properties  These properties are what makes light…well, light  We will be doing some experiments that have to do with some of these properties later Wait, There’s More?

 Here are some of the properties of light:  It has brightness, color, and visibility  It travels in a straight line  It can be reflected, refracted, and absorbed Wait, There’s More?

 Here are some more of the properties of light:  It can pass through certain materials  It can also be blocked by certain materials Wait, There’s More?

 …And last but most certainly not least:  If it is white, then it is actually a mixture of all the colors (ROYGBIV!)  Again, if its white, then the colors can be separated using a prism Wait, There’s More?

 The first property we are going to look at is:  Light travels in a straight line  For our first experiment, you will need:  4 Index Cards  Play Clay  Ruler  Pencil  Flashlight  Now that we have those items, let’s get started! Bullseye!

 Here are the steps for our first experiment:  Draw diagonal lines on 4 index cards, connecting the opposite corners  Draw a bullseye on one of the cards in the exact center  Poke a hole in the exact center of the other three index cards  Place 4 lumps of play clay in a line and place the index cards on the clay  With the lights out, shine your flashlight at the first card and see if you can hit the bullseye with the light  Adjust the cards if you did not succeed the first time Bullseye!

 How must the cards be placed so that the light shines through the holes? Bullseye! Question One

 What property of light does this experiment demonstrate? Bullseye! Question Two

 How can a shadow help show that light travels in a straight line? Bullseye! Question Three

 The next property we are going to look at is:  Light can be reflected  For our second experiment, you will need:  Index Cards  Play Clay  Laser Pointer  Mirror  Flashlight  Aluminum Foil  3 Sheets of Paper (White, Black, Color) A Moment for Reflection

 Here are the steps for our second experiment:  Predict which of your materials will be good reflectors, rank them from worst reflector to best reflector  Set up a cue card on a lump of play clay, this will be used as a screen  Place the mirror in another lump of play clay, such that when you shine your flashlight on the mirror, the light is reflected onto the cue card  Look at the light reflected on the card, noting the brightness and the shape of the reflection  Repeat steps 3 and 4, replacing the mirror with the other surfaces, and compare your results to those of the mirror  Re-rank the materials using your results  Write a few sentences about what you discovered, or what you have learned A Moment for Reflection

 What did you discover by doing this experiment? A Moment for Reflection Question One

 What would the be difference between the reflections of flat aluminum foil and wrinkled aluminum foil? A Moment for Reflection Question Two

 Why do we paint yellow lines on our black roads? A Moment for Reflection Question Three

 That takes care of two properties of light!  For the next two lessons, we will do more experiments on the other properties of light Well Done!

 Let’s have a quick refresher before we wrap this lesson up  Light is a type of energy we can see  Light sources can be natural or manmade  Light travels in a straight line  Light can be reflected Well Done!

Until Next Time…

Light: What Is It and How Does It Work? Lesson Two

 Before we begin experimenting with more properties of light, let’s look back at what we learned in the last lesson:  Light is a type of energy we can see  Light sources can be natural or manmade  Light travels in a straight line  Light can be reflected Previously On…

 Today, we will be experimenting with three more properties of light:  It can be refracted  It can pass through certain materials  It can also be blocked by certain materials This Time On…

 Consider the following scenario:  A fisherman is using a spear to catch fish. Instead of throwing his spear directly at the fish in the water, he throws it in front of the fish and hits it. Why is this?  Take a moment to share some of your thoughts on the question with your neighbor and then we will find out what the rest of the class thinks The Water Broke My Pencil!

 The reason that the fisherman throws his spear in front of the fish is the same reason that a pencil placed in a glass of water appears broken The Water Broke My Pencil!

 The reason is refraction and it simply means that light bends as it passes through different materials The Water Broke My Pencil!

Convex Lenses  Convex lenses curve outward  Light that strikes a convex lens begins to bend inward Concave Lenses  Concave lenses curve inward  Light that strikes a concave lens begins to bend outward Refraction is something we often use to benefit us and one of the ways that we do this is through the use of convex and concave lenses. Lenses are pieces of transparent material that have at least one curved surface.

 The third property we are going to look at is:  Light can be refracted  For our third experiment, you will need:  Rubber Band  Plastic Containers  Small Objects  Water  Newspaper  Pipette The Water Broke My Pencil!

 Here are the steps for our third experiment:  Place the small objects in the bottom of the plastic container  Draw what you see  Cover the plastic container loosely with plastic wrap and use the rubber band to hold it in place  Gently pour water on the plastic wrap, notice that the top of the water is flat, yet the bottom is curved  Look at the small objects in the bottom of the container  Draw what you see  Experiment to see if you can make your lens more or less powerful  Answer the discussion questions The Water Broke My Pencil!

 Why does your view of the objects change after adding the plastic wrap and water? The Water Broke My Pencil! Question One

 What kind of lens was made during this experiment? Explain your reasoning The Water Broke My Pencil! Question Two

 Using the same principles you have used to make this magnifying lens, can you make a magnifier to make it easier to read a newspaper? Test your idea, then draw the results The Water Broke My Pencil! Question Three

 Remember the two properties of light mentioned earlier that dealt with materials being able to either allow light to pass through them or not?  Well, the materials that allow light to pass through them are called transparent and translucent while the ones that don’t are called opaque “I Can See Clearly Now…”

 Transparent Materials  They allow light to pass through them in straight lines which means you can see clearly through them  Glass is the best example of a transparent material “I Can See Clearly Now…”

 Translucent Materials  They allow some light to pass through them  The light is scattered which means you cannot see clearly through them  Tissue paper is a good example “I Can See Clearly Now…”

 Opaque Materials  They do not allow light to pass through them  Instead, they block the light which means you cannot see through them  Wood is a great example of an opaque material “I Can See Clearly Now…”

What kind of materials are these?

 The next two properties we are going to look at are:  Light can pass through certain materials  Light can also be blocked by certain materials  For our fourth experiment, you will need: “I Can See Clearly Now…”

 Here are the steps for our fourth experiment:  Use the flashlight to determine what objects are transparent, translucent, and opaque  Using your observations, fill out the table you are given “I Can See Clearly Now…”

 That takes care of three properties of light!  For the next lesson, we will do one final experiment on another property of light  Let’s have a quick refresher before we wrap this lesson up  Light can be refracted  Light can pass through certain materials  Light can also be blocked by certain materials Well Done!

 Let’s have a quick refresher before we wrap this lesson up  Light can be refracted  Light can pass through certain materials  Light can also be blocked by certain materials Well Done!

Until Next Time…

Light: What Is It and How Does It Work? Lesson Three

 Before we begin experimenting with one last property of light, let’s look back at what we learned in the last lesson:  Light can be refracted  Light can pass through certain materials  Light can also be blocked by certain materials Previously On…

 Today, we will be experimenting with one more property of light:  White light is a mixture of all the colors and can be separated using a prism  Now you might be asking:  What’s a prism? This Time On…

 A prism is a block of glass or clear plastic that usually has rectangular and triangular sides  When white light passes through a prism, it bends and all of the colors in it become visible  The separation occurs because each color bends by a different amount What Do Prisms Have To Do With Rainbows?

 When you see a rainbow outside, it’s because tiny little water drops left by rain showers are acting as natural prisms for the sunlight What Do Prisms Have To Do With Rainbows?

 Now, before we begin our final experiment, let’s take a moment to talk about those colors that we see when white light is separated and how they relate to the things around us Colors: More Than Meets the Eye

 The colors of an object are determined by the colors of light that are reflected when it is struck by white light  Certain colors are reflected and the rest are absorbed by the object  These reflected colors of light are what reach our eyes and cause us to see them as those particular colors  Crazy, right? Colors: More Than Meets the Eye

 An example would probably be the best way to explain this:  I really like the color blue so most of my clothing is blue  The reason that my clothes are blue is because white light strikes them and blue light is reflected  The other colors in the white light are absorbed by my blue clothes  We all see them as blue because the blue light that is being reflected is what reaches our eyes Colors: More Than Meets the Eye

 Okay, so now we understand why we see the different colors of light in the things around us but…  Why do colors exist in the first place?  Well, the answer is simple:  Colors are produced by certain amounts of light energy Colors: More Than Meets the Eye

 These are how each of the colors stack up to one another in terms of energy:  Red (Least Energy)  Orange  Yellow  Green  Blue  Indigo  Violet (Most Energy) Color: More Than Meets the Eye Increasing Energy

 An easy way to remember this energy ranking of colors is ROYGBIV  This also happens to be the pattern of the colors in a rainbow Color: More Than Meets the Eye

 The final property we are going to look at is:  White light is a mixture of all the colors and can be separated using a prism  For our fifth and final experiment, you will need:  A Window with Plenty of Sunlight  Large Bowls of Water  Small Mirrors  Sheets of White Paper Release the Rainbow!

 Here are the steps for our fifth and final experiment:  Place the bowl of water near the window with the most sunlight coming through  Place the small mirror in the bowl of water so that it faces the sunlight  Hold the white sheet of paper above the bowl so that the sunlight reflects off of the mirror and hits it  Answer the discussion questions Release the Rainbow!

 What appeared on the white sheet of paper when you held it above the mirror in the bowl of water? Release the Rainbow! Question One

 What was used as the prism in this experiment? Release the Rainbow! Question Two

 Based on your experience with this experiment, what type of light would you classify sunlight as? Why? Release the Rainbow! Question Three

 That takes care of the final property of light!  Let’s have a quick refresher before we wrap this lesson up:  It has brightness, color, and visibility  It travels in a straight line  It can be reflected, refracted, and absorbed  It can pass through certain materials  It can also be blocked by certain materials  If it is white, then it is actually a mixture of all the colors (ROYGBIV!)  Again, if its white, then the colors can be separated using a prism Well Done!

Until Next Time…