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# Refraction and Rainbows

Lesson 6 of 11

## Objective: SWBAT explain the similarities and differences between refraction, reflection and diffraction.

## Big Idea: In this hands on lesson, students work to discover how rainbows are made, discover what happens to the way a pencil looks when half of it is placed in water. .

*75 minutes*

#### Engage

*5 min*

I begin this lesson by reviewing what electromagnetic waves are. I tell students that a wave of light will travel in a straight line until it encounters an obstacle or is encountered by a force. Then I show this video.

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For this part of the lesson, I give students 2 glass beakers and 2 pencils, although any straight object will work. (I prefill the beakers since my classroom only has one sinc. I fill one beaker with water, and leave the other empty.) Next, I instruct students to place the pencil into the empty beaker and observe it from the side. I direct students to write some observational notes in their science notebooks about how the pencil looks. Then, I direct students to put the other pencil in the water and look from the **same **angle. Students should be able to see a bend in the appearance of the pencil, especially if they focus at the water line. I instruct students to write brief observational notes in their science notebooks about the pencil in the water.

Listen in as this students tries to explain what is happening. He notices a difference in how the pencil looks but struggles to come up with exactly what he wants to say.

Next I show students the refraction handout (Refraction handout Explanation) and lead a brief discussion about refraction. I ask students to explain refraction in their own words by writing about what they observed in their notebooks.

Next, I tell students that rainbows form when light is **refracted **off raindrops. If the sun is at the right angle, different drops will refract different colors. Then I show this video about how rainbows are made to help clear up misunderstandings about refraction.

insert student video of refraction definition here)

#### Resources

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#### Evaluate

*10 min*

As students make observations during this lesson, I informally assess their knowledge of the information presented. Since NGSS 4-PS4-2 states that students will develop a model to describe that light reflecting from objects and entering the eye allows objects to be seen, as I'm informally observing students, I focus on whether or not students understand reflection.

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- LESSON 1: What are Waves?
- LESSON 2: Properties of Waves
- LESSON 3: What is Visible Light?
- LESSON 4: Creating Simple Spectroscopes
- LESSON 5: Using Simple Spectroscopes
- LESSON 6: Refraction and Rainbows
- LESSON 7: Light Reflection
- LESSON 8: Sound Waves - Part 1 Density
- LESSON 9: Sound Waves - Part 2 Intensity
- LESSON 10: Waves Performance Assessment Part 1
- LESSON 11: Waves Performance Assessment Part 2