Abstract
Waves and wavelike motion surround us. Many phenomenons can be modeled using the wave motion concepts. Energy, such as light from the sun, travels in waves. This is a way to bridge the gap between the physics curriculum of waves and wave motion, and the environmental health theme of electricity generation and its trade-offs. This waves introduction will lead to the study of photovoltaic cells, UV light, and microwaves. These waves are associated with several environmental health issues. Understanding the basic physics behind these energy sources creates an understanding of how an environmental factor can impact human health. Students will design an experiment using the materials provided to explore waves.

Objectives
Students will be able to:
1. Define amplitude, wavelength, frequency, and period.
2. Calculate the period given the frequency, and calculate the frequency given the period.
3. Define crest and trough and locate them on a diagram of a wave.
4. Differentiate between latitudinal and longitudinal waves.
5. Design an experiment on waves and wave motion.

National Science Education Standard
Content Standard A-Science as Inquiry
ABILITIES NECESSARY TO DO SCIENTIFIC INQUIRY

• IDENTIFY QUESTIONS AND CONCEPTS THAT GUIDE SCIENTIFIC INVESTIGATIONS. Students should formulate a testable hypothesis and demonstrate the logical connections between the scientific concepts guiding a hypothesis and the design of an experiment. They should demonstrate appropriate procedures, a knowledge base, and conceptual understanding of scientific investigations.
• DESIGN AND CONDUCT SCIENTIFIC INVESTIGATIONS. Designing and conducting a scientific investigation requires introduction to the major concepts in the area being investigated, proper equipment, safety precautions, assistance with methodological problems, recommendations for use of technologies, clarification of ideas that guide the inquiry, and scientific knowledge obtained from sources other than the actual investigation. The investigation may also require student clarification of the question, method, controls, and variables; student organization and display of data; student revision of methods and explanations; and a public presentation of the results with a critical response from peers. Regardless of the scientific investigation performed, students must use evidence, apply logic, and construct an argument for their proposed explanations.
• USE TECHNOLOGY AND MATHEMATICS TO IMPROVE INVESTIGATIONS AND COMMUNICATIONS. A variety of technologies, such as hand tools, measuring instruments, and calculators, should be an integral component of scientific investigations. The use of computers for the collection, analysis, and display of data is also a part of this standard. Mathematics plays an essential role in all aspects of an inquiry. For example, measurement is used for posing questions, formulas are used for developing explanations, and charts and graphs are used for communicating results.
• FORMULATE AND REVISE SCIENTIFIC EXPLANATIONS AND MODELS USING LOGIC AND EVIDENCE. Student inquiries should culminate in formulating an explanation or model. Models should be physical, conceptual, and mathematical. In the process of answering the questions, the students should engage in discussions and arguments that result in the revision of their explanations. These discussions should be based on scientific knowledge, the use of logic, and evidence from their investigation.
• RECOGNIZE AND ANALYZE ALTERNATIVE EXPLANATIONS AND MODELS. This aspect of the standard emphasizes the critical abilities of analyzing an argument by reviewing current scientific understanding, weighing the evidence, and examining the logic so as to decide which explanations and models are best. In other words, although there may be several plausible explanations, they do not all have equal weight. Students should be able to use scientific criteria to find the preferred explanations.
• COMMUNICATE AND DEFEND A SCIENTIFIC ARGUMENT. Students in school science programs should develop the abilities associated with accurate and effective communication. These include writing and following procedures, expressing concepts, reviewing information, summarizing data, using language appropriately, developing diagrams and charts, explaining statistical analysis, speaking clearly and logically, constructing a reasoned argument, and responding appropriately to critical comments.

Content Standard B-Physical Science
INTERACTIONS OF ENERGY AND MATTER

• Waves, including sound and seismic waves, waves on water, and light waves, have energy and can transfer energy when they interact with matter.

Teacher Background
None.

Related and Resource Websites
http://www.glenbrook.k12.il.us/gbssci/phys/Class/waves/wavestoc.html (simple tutorial on waves).

Activity
Day 1
1. Organize students into groups of 3 or 4. Have one student from each group be responsible for getting and returning materials. Each group should get the following:

• a phone cord
• a slinky
• a ruler
• a stopwatch
• a length of string
• a jump rope
• a container for water
• a pebble or marble

2. Let students know they will be experimenting with waves. They should have some background knowledge of waves, and might already know some of the vocabulary words from the lesson objectives. Instruct students to discuss with their groups what they know about waves. Monitor the discussions to get an idea of background knowledge and misconceptions. You may have them create a concept map on what they know about waves.

3. After students discussed in their groups, let them experiment with the materials. They are to use their equipment to generate waves. Although the experiment is open-ended, encourage them to record observations and questions. Because they have been given little direction, allow them the rest of the first day to “explore” and develop a testable question. There are endless possibilities for testable questions, but here are some ideas to help the class arrive at the objectives:

1. In what material do waves move the fastest or slowest?
2. How will a wave behave when traveling through two different mediums?
3. What determines the length, speed and height of the waves?
4. Do latitudinal or longitudinal waves travel faster? (correct vocabulary might not be here yet, but students will see the difference)
5. At what rate do waves diminish? What influences this rate?
6. What happens when two or more waves collide?

There are many, many more—whatever your students come up with.

4. Monitor the groups and ensure by the end of the first day each group has a testable question. They will be designing an experiment next class.

Day 2
1. Have students get in their groups, gather previous day’s materials and review their testable question.

2. The groups should form a hypothesis based on their observations from last class. They should develop an “if….then…” statement. What do they expect to find from experimenting?

3. Students should provide a written experiment design. Monitor groups and ensure their experiment idea will successfully test their hypothesis. Some guided questions:

• What will be the procedure?
• How many variations will be needed for this procedure?
• How many trials should occur for each variation?
• How will observations be record?
• If hypothesis is supported, what will be the results?
• If hypothesis is false, what will be the results?

4. Once the groups have determined an acceptable experimental procedure, they may begin. Allow the class remainder to obtain and record their observations.

5. Watch the clock and allow a few minutes for them to clean up and return materials.

Day 3
1. Allow students to get in their groups and gather materials.

2. Students should finish their experiments in the first half of class. As groups complete their experiments, have them begin a lab write-up. The format for this is up to the teacher.

3. Once all students finished their experiment and made significant progress on the lab report, they should report their results. Since this was an open-ended experiment, the testable questions and discussion will vary. However, it is essential to ensure objectives are met. One suggestion on guiding this discussion is introduce vocabulary words as they arise and have students write them in their notes. Science vocabulary is like another language for students. An open-ended discussion will help students see the importance of the specific terms. To discuss observations, they need to have a common vocabulary. Those words include wavelength, amplitude, crest, trough, and Hertz and they should use the appropriate terms in the lab reports.

4. Depending on the group, one objective that might not come up in any of the experiments, at least not directly, is the one dealing with the relationship between period and frequency. Once students defined the words, find a group with data of these two measurements. Their relationship should be obvious with good data; one is the reciprocal of the other.

5. Some concepts may arise, such as interference, wave behavior at the intersection of two mediums, or standing waves that will be addressed in future lessons. Let each group’s research ellicit more questions and curiosity from the class for later lessons.

Closure
Each group presentation and the notes taken on vocabulary words serve as lesson ‘s closure. Ask students to incorporate what they learned into the concept map they drew at the beginning.

Homework
Practice labeling wave parts and period and frequency calculations and finish lab reports.

Embedded Assessment
Students’ prior knowledge about waves can be assessed in the concept maps created at the beginning of class. Informal group observations during design process and exploration provide a venue to assess students’ experiment design and hypothesis development. The lab report has student assessment on matching of hypothesis to a test. Students’ concept understanding can be assessed by appropriate term use in the lab report and in the final concept map.

The Community Outreach and Education Program is part of the Southwest Environmental Health Sciences Center: an NIEHS Award

Supported by NIEHS grant # ES06694