Chapter 10, Lesson 5, "How Light is Reflected"
Materials:
Objective:
Anticipatory Set:* Show a picture of a baby looking in a mirror ask which of the baby's arms is supporting the baby's body? Which ear can you see in the mirror? Which ear can you see directly? Which foot is visible in the picture? There is a small round toy close to the baby. Even though the picture is in only two dimensions could you describe all sides of the toy? What does a mirror do to an image? Show the image of writing and describe how it is different. This artist used a mirror for inspiration in the poem. Is it a mirror image?
Teacher Input:* Today we are going to learn how to interpret light as it reflects of certain surfaces. First of all we need to figure out what type of surface will reflect light? Show three picture of a reflection on a lake ask the students to pay close attention to the pictures and figure out what all three lakes have in common. Picture 1, Picture 2, Picture 3. Next show this rough lake or this one of a rough lake with no reflection and ask what the difference is? Point out that in order for light to bounce back an provide a reflection it must have a smooth surface. There are many things around use that we can see to help explain how light bounces of of a surface. Here we se Michael Jordan dribbling the basketball bounces off the floor in a predictable way. If the surface of a gym floor were like this it would be a lot harder to figure out where the ball is bouncing back up. The game breakout also uses the same principle. There is a good picture on Page 294 that shows how light reacts on a smooth surface. So light photon hitting a smooth surface bounce of together with the same angle and light waves hitting a rough surface get scattered. When we look at a rough lake we see a scattering of light which can gives differing shades of light and dark. When the light bounces of of a smooth surface like a mirror it gives us a good image but because of the reflection the image is reversed. A mirror like this is called a plane mirror because it is flat, and smooth.
Mirrors do not always have to be flat sheet in a plane. As long as they are smooth they will reflect the light in an organized way allowing use to see an image. In a concave mirror the surface is smooth but curved inward. (Think of it like a cave) When light rays bounce off of a concave mirror they all come together at a single point in space. this is called the Focal point. Depending on where you view a reflection in a concave mirror you will get differing results. Follow the light rays through these concave mirrors to determine how you would see the object. In front of focal point. In front again. Behind the focal point.
Another type of mirror is a convex mirror. A convex mirror creates an image that is smaller than the real object but you can see much more area that is why they are very useful for the side-view mirror of a car because they allow you to see more of the area next to the car which would otherwise be in your blind spot while driving.
Guided Practice:* Students will answer the questions on Page 298 as a group.
Independent Practice:* Students will read the selection while they are working on the worksheet 10-05 "How Light is Reflected".
Check for Understanding:* Students will take the quiz, 10-05 "How Light is Reflected"
Duration:
30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).
Alaska Content Standards Addressed in this lesson:
