SLMS 7th Grade ScienceEnergy Effects

Unit 2 Light travels in a straight path.

Waves and how they relate to light waves

P.EN.07.11P.EN.07.21 and 22

Part 1What do you know?

ODiscuss the following statement.

We know that the sun produces light through nuclear reactions that occur on and in the sun. How does the light produced travel to or reach Earth?

O Record your ideas on the What we think…

chart.

Ask yourself… - What observations have you made to help explain this question? - How do shadows help explain how light travels - How do you know that a flashlight will shine on what you are looking for? - Can you think of another example that demonstrates how light travels?

Teacher CheckO Light travels in …………

O Light sometimes makes……..

O What do we see light doing in nature?

(through clouds, tree branches, windows)

Flashlight LabO Work in teams of 2.O Design a demonstration that gives evidence of how light travels.

O You will need: - A flash light - Three note cards with holes - One note car with a slit in it - One sheet of white construction paper - Tape - A measuring tape

O Ask yourself…… - Can you explain what you have discussed and assembled so far? - How will you set up your demonstration? - Can you think of other ways to demonstrate this? - How would you describe your demonstration? - What do you already know about how light travels? - What path will your light take? - What would happen if you changes things in your demonstration? - Have you discussed you challenges with another team?

Record your demonstration in your journal

O What did your demonstration show?

O Draw and label the set up for your demonstration.

O Explain how your demonstration answers

the question: How does light travel?

Present your demonstration to the neighboring group.O Record you conclusions on the What

We Think About How Light Travels chart.

O Watch the following video and compare the student demonstrations to the video.

http:/teachersdomain.org/resource/lsps07.sci.phys.energy.lighttravel/

Part 2Light travels in a straight path.

Light moves in waves.O Explain how can light travel in a straight line and

in waves.

A B

QUESTIONS

1. Can we still describe how light travels in a straight path, using waves?

2. Does the concept still make sense? Why or why not?

3. Can anyone describe or explain what makes up a wave?

Teacher DemonstrationWaves on Water

O How did the movement from the disturbance travel outward?

O Draw a diagram of the wave pattern. (Top View)

Slinky FunCaution!

Do Not Overstretch the Slinky

Materials: One slinky and a measuring tape

- One student should hold the slinky while the other student waves or vibrates the slinky.- Read directions on the next slide.

Slinky Directions1. Place slinky on floor and stretch so that the rings are 1cm apart. (DO NOT OVERSTRETCH!)2. One student makes a back and forth motion for a distance of 15cm. Observe the wave motion3. Make short quick back and forth movements. Make a chart and record observations.4. Switch positions and repeat. 5. Draw and label several waves. Label at least one trough and one peak.6. Describe the relationship between the length (wavelength) and the height (amplitude).7. Share your observations with the class.

Word Sort CardsO Discuss the key terms and

Organize/Categorize the terms using the cards.

O Ask yourselves: 1. How are the terms related?

2. Why did we group the cards like this?

Read the journal selection called

Light and WavesO Summarize the properties of waves.

O Explain: 1. How does light travel from the sun to the Earth?

2. How does the Earth get heated?

Wave SimulatorsWave Simulator

Waves on a String

Wave Art in Grand Rapids

Discuss: Wavelength and Frequency and how they relate to how light energy travels in waves.

Remember this?

O Identify: 1. Amplitude 2. Frequency 3. Wavelength

Reading TimePrinciples of Light

Part 3Youtube Demonstration

O Light Reflection on a Plane Mirror

Wrap Up DiscussionWhat you know Chart

1. Record ideas for your demonstrations.2. We now understand that light travels in a ________ ____ and in _____.3. How are light waves different than waves on water?4. How is the Earth heated?5. How does light travel from the sun to Earth?

Next we will study Brrrrrrrrrrrrrrrrrrrrrrrrrr Pshhh.

ELECTROMAGNETIC WAVESOF LIGHT

Or

THEELECTROMAGNETIC

SPECTRUM