ABSTRACT:
Solar energy is a renewable resource available today, waiting to be discovered by the masses. Background information as well as current solar energy options is presented in an active, hands-on format for students in grades 8 or 9. Learner outcomes will be measured utilizing alternative assessment. The culminating activity will involve groups creating a solar collecting device utilizing the following concepts: angle of the sun's rays, energy absorbing colors, insulation and reflection.

MATERIALS: See individual labs.

LEARNER OUTCOMES:

1. build a gnomon to calculate the angle of the sun 2. evaluate solar technology problems involving active and passive transport and solar cells 3. construct a solar collection device 4. analyze and apply the concepts of absorption, angle of rays and reflection

PROCEDURE:

The terms Oil Spills, Nuclear Contamination, Global Warming, and Acid Rain have become part of our vocabulary thanks in part to the news media. Our demand for energy has brought about these side effects and we seem unable to cope with these problems or to change our energy demands. The US consumes 70 million barrels of oil a day, at this rate depleting our national reserves in less than 27 years. Weekend mechanics dump an Exxon Valdez oil spill down our sewers every two and a half weeks. The list goes on and on. Traditional sources of energy are really "second hand" solar energy. The international concern of clean energy has become an issue and this unit is intended to open some eyes and spark an interest in a renewable energy available to everyone.

Unit Requirements:

1. assessment of prior knowledge 2. introductory activity 3. required readings 4. VHS Electricar 5. successful completion of required labs -- learner outcome #1 6. evidence of completion of two other lab experiences 7. laboratory assessment -- learner outcome #2 8. contest assessment -- learner outcome #3 & 4 9. assessment of conceptual development

1. Assessment of prior knowledge -- An assessment will be given to determine prior knowledge and/or misconceptions. The assessment includes the following: Fact/Fiction, Possible/Not Likely, Energy Source Check List and Short Answer.

2. Introductory activity -- Take students outside and set up a solar toy such as Funlab by Skilcraft. The reflector and solar rays turn water inside the "bird" to steam, causing movement. Have student work in groups to describe what happened. Collect and return at the end of the unit and ask students to evaluate the discrepancies.

3. Required readings -- Pamphlets from the U. S. Department of energy entitled Learning About Renewable Energy and Solar Energy and You provide technical descriptions of solar energy. Information on passive and active transport, solar collection devices, solar cells and solar water heaters is also included in these publications. Trade books will be used for design plans, lab activities and extensions.

4. VHS Electricar: Solar Systems -- from Earth Options. Interviews with electric vehicle owners and footage of Electricar vehicles are shown in the video as well as environmental and health benefits of EV's. An overview of the solar energy industry is shown along with additional ways solar energy can help save energy and money.

5. Required labs: a. What color absorbs the sun's heat best? Group students and freeze 30 mL of water in a small medicine cup (4 cups per group). Remove the ice and place each into a zip seal bag. Each group needs a set of background materials upon which to set the bag. Background materials include black and white paper, foil and glass. Record the time necessary to melt the ice. Graph the data and discuss the results.

b. What water temperature increase would you expect after 20 minutes in a solar water heater? Students will observe a solar water heater and generate numerous questions concerning solar water heaters and water temperature. Groups will classify their questions into three categories of their choice. Students may find solutions to their questions using reference materials or student experts. Oral reports on the most interesting finding or challenging question will be shared and discussed with the class. Predictions of water temperature increase will be made by individuals and followed by a group prediction with a short explanation defending that position. The teacher will then describe the process while setting up the heater and students will be encouraged to participate through the sharing of expertise and asking additional questions. Results will be discussed in groups and conclusions shared with the class.

c. How does the angle of the sun's rays relate to solar collection devices? Part 1 -- Building a Gnomon - Measuring the angle of the sun's rays must be completed on the day prior to the second part of this lab. Time of year and time of day will affect the test. Each group will need two meter sticks, set with one on the ground and the other perpendicular. Adjust and measure the shadow cast. Calculations: Altitude = 1 meter Distance = shadow length Tangent Theta = Altitude divided by Distance Use the Table of Trigonometric Ratios and the Tangent Theta value to find the angle of the sun's rays. To determine placement of the solar collection device, the student needs to recall that the sun's rays should be perpendicular to the flat surface of the collector. The ground is the baseline and the sun's angle must be drawn into this baseline. A 90 degree angle is drawn next, representing the flat surface of the collector. The complementary angle formed determines the slope of the collector.

Example:

Part 2 -- Placement of the three simple solar collectors will be 1)at the determined angle, 2)plus 10 degrees and 3)minus 10 degrees. The collectors will be made using cardboard to be bent at the base, resulting in the desired angles. The cardboard is to be covered with black paper and a thermometer taped to each of the three. Place in direct sunlight and take temperature readings every minute for five minutes.

d. Can solar energy be converted to electrical energy? Use a battery operated device such as a toy to demonstrate the use of a solar cell. Show the device working with batteries and list the pro's and con's of batteries. Detach the battery and connect the solar cell and operate the device. Increasing and decreasing the light source should be demonstrated prior to listing pro's and con's of solar cells. Brainstorm possible applicable conversions to solar cells.

6. Two additional lab experiences -- These labs are designed to allow the students the opportunity to explore different avenues of interest in the area of solar energy. Sources for the lab activities may come from required readings, trade books, teacher lab activity books or student sources. The labs may be conducted at home or in the classroom. All labs must be approved by the teacher and follow safety requirements set up in the student handbook. Evidence of lab work can take on many different formats and allow for a variety of experiences.

7. Laboratory assessment -- Students will report to lab stations and analyze solar technology problems involving active and passive transport and solar cells.

Station #1: Use the drawing of the school to determine if the placement of the greenhouse was random or specific. Support your position with specific information you acquired from readings, lab activities or other sources.

Station #2: Position the model house so that optimal active solar transport will occur. Explain active solar transport and describe why your heater position choice is optimal.

Station #3: Draw your home, explain passive solar transport and describe how it affects your home.

Station #4: Describe the solar electricity process for the item displayed. List three additional solar energy conversions possible today or in the near future.

8. Contest assessment --Each group will be given a set of materials containing the following items: black paper, white paper, foil, plastic wrap, tape, a shoe box, starch packaging materials, test tube, stopper, paper towel roll, string, rubber band, paper clips, and a few other items that are not needed but add interest. The groups are required to construct the device in one class period and consider concepts such as the angle of the sun's rays, energy absorbing colors, insulation and reflection. The test tube of water must be placed in the device on this day. On the second day, groups will carefully position their collector outside. Meanwhile, they will judge each group's collector, writing strengths and weaknesses of each design. Five minutes before the end of class, each group will be required to remove their tube of water and record the temperature. The solar device with the greatest increase in temperature will be declared the winner. The following day prizes will be awarded and designs discussed. Each group will submit a short report describing design flaws and possible changes. If students express an interest in redesign and testing, time will be set made available for retesting.

9. Assessment of Conceptual Development and Misconceptions- An assessment will be given to determine conceptual growth and identify misconceptions. The assessment includes the following: Fact/Fiction, Possible/Not Likely, an Energy Source Check List and Short Answer.

EXTENSIONS:
Sun sensitive paper reacting with ultraviolet solar rays demonstrates how light energy can be directed to produce visible chemical changes. While waiting for the contest devices, you may want to cook marshmallows using parabolic mirrors with differing focal lengths. These mirrors may be constructed and tested as part of the additional required labs. Students may research other renewable resources.

REFERENCES:
Clean Energy: No Longer a Luxury! Resources in Technology. Technology Teacher, V50 n4, Jan 1991, p15- 22.

Flavin, C., Lenssen, N. Beyond the Petroleum Age: Designing a Solar Economy. Worldwatch Paper 100., ED327374.

Hoots, R. A., White Prints. Science Teacher, V58 n1, Jan 1991, p 16-19.

Learning About Renewable Energy. US. Department of Energy, DOE/CE-0272, FS 189, 2nd Edition, Oct 1989.

Passive and Active Solar Domestic Hot Water Systems, US. Department of Energy, DOE/CE-0228, FS 119, 3rd Edition, Aug 1988.

Solar Energy and You. US. Department of Energy, DOE/CE-0093/1, FS 118, 3rd Edition, Mar 1992.

Solar Energy II. Illinois Department of Energy and Natural Resources.

Technology Learning Activities. Technology Teacher, V50 n5, Feb 1991, p5-8.

What's Your Energy I.Q.? Conservation and Renewable Energy Inquiry and Referral Service, P.O Box 3048, Merrifield, VA 22116.

MATERIALS REFERENCE:

Earth Options, 6930 McKinley Street, Sebastopol, CA 95472 For Electricar VHS tape.

Skilcraft, division of Monogram Models, Inc., DesPlaines, IL 60016 For Funlab "bird".

Solargraphics, P.O. Box 7091P, Berkeley, CA 94707 For sun sensitive paper.

SUBMITTED BY:
Susan Knorr, Quincy Junior High, 100 South 14th Street, Quincy, IL 62301 (217)222-3073.