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Grade Level(s): 6-8
Introduction: Waves are a source of enjoyment for many beach goers. They provide a mechanism with which people can surf and enjoy an action-filled day in the ocean. Ocean waves develop when wind exerts a shearing stream across the ocean surface. Wind speed variations, often referred to as turbulent fluctuations, cause pressure differences to develop on the ocean leading some areas of water to be higher than others. As the wind continues to blow, pressure differences between the trough and crest of the waves cause them to grow. After wind speed decreases, waves subside and the energy of motion is dissipated along the shorelines by internal friction.
Learner Objectives:
- The student will be able to predict the effects of force on water and waves.
- The student will be able to test the effects of velocity on waves.
Florida Sunshine State Standards: Math: MA.E.1.3.1 Science: SC.H.1.3.5.
Competency Based Curriculum: Math: M/J-1 - V-2-A-b, M/J-3 -VI-2-A; Science: M/J-1 - I-8-A
Materials:
clear baking dish
food coloring
4 straws
4 pencils
Activity Procedures:
- Begin discussion of surfing and water parks and have students relate experiences orally.
- Question students as to how the waves are created at the parks.
- Show illustration of an wave and introduce the following vocabulary:
- crest - the highest point of the wave
- trough - the lowest point of the wave
- height - the distance from the crest to the trough
- wavelength - the distance between the crest of one wave to the crest of another
- period - the time it takes a wave to pass a fixed point
- Fill a glass baking dish with colored water and place it on an overhead projector.
- Have the students predict how the water will react to objects touching it with different forces and in different locations.
- Next, as the following is done, have students test their predictions as they observe and record their observations.
- Tap water lightly in the center with a pencil.
- Tap water harder in the center with a pencil
- Tap water lightly but close to one side of the dish.
- Tap water harder but close to one side of the dish.
- Tap two pencils, each about an inch from the center, at the same time with the same force
- Tap two pencils, each at opposite ends of the dish, at the same time with the same force.
- Tap two pencils, each about an inch from the center, at the same time, but use more force with one than the other.
- Repeat the previous step but tap the pencils individually, five seconds apart.
- Blow straight down on the water with a straw from two inches above.
- Repeat the previous step while blowing straight across the water.
- Have two students repeat the step. Increase the number of students blowing to four.
- Discuss observations and address predictions.
- Close with a discussion including the following questions:
- Can you define a wave?
- How does the force of an object acting on water affect the wave that it creates?
- How does the force of air on water affect the waves that it creates?
- How do wave pools work?
- How do the intervals and positions of air bursts effect the waves that are created in wave pools?
Student Assessment:
- Check students data on observation sheets.
- Assess mastery of vocabulary either orally, by having students write brief paragraphs on the topic, or by giving a vocabulary quiz.
Activity Extensions:
Have students design a wave pool. The students must give course design, positioning of air jets, and dimensions. The students should name and present their creation to the class.
Home Learning Activity:
Have students prepare to present their creation to the class.
Vocabulary: crest, trough, wave length
References/Related Links:
http://www.the-sea.org
http://www.cln.org/themes/earlynavigation.html
www.aquanet.com
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