SLMS 7th Grade Science Energy Effects Unit 2 Light travels in a straight path. Waves and how they relate to light waves P.EN.07.11 P.EN.07.21 and 22

Part 1 What do you know? Discuss 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 by the sun travel to or reach Earth?

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 Check Light travels in ………… Light sometimes makes…….. What do we see light doing in nature? (through clouds, tree branches, windows)

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

- Can you explain what you have discussed and 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 What did your demonstration show? Draw and label the set up for your demonstration. Explain how your demonstration answers the question: How does light travel?

Present your demonstration to the neighboring group. Record you conclusions on the What We Think About How Light Travels chart. Watch the following video and compare the student demonstrations to the video. http:/teachersdomain.org/resource/lsps07.sci.phys.energy.lighttravel/

Part 2 Light travels in a straight path. Light moves in waves. Explain how can light travel in a straight line and in waves. A B QUESTIONS Can we still describe how light travels in a straight path, using waves? Does the concept still make sense? Why or why not? Can anyone describe or explain what makes up a wave?

Teacher Demonstration Waves on Water How did the movement from the disturbance travel outward? Draw a diagram of the wave pattern. (Top View)

Slinky Fun Caution! 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 Directions 1. 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 motion 3. 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 Cards Discuss the key terms and Organize/Categorize the terms using the cards. Ask yourselves: 1. How are the terms related? 2. Why did we group the cards like this?

Read the journal selection called Light and Waves Summarize the properties of waves. Explain: 1. How does light travel from the sun to the Earth? 2. How does the Earth get heated?

Wave Simulators Wave 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? Identify: 1. Amplitude 2. Frequency 3. Wavelength

Reading Time Principles of Light

Part 3 Youtube Demonstration Light Reflection on a Plane Mirror

Wrap Up Discussion What 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 WAVES OF LIGHT Or THE ECECTROMAGNETIC SPECTRUM