Classroom Activities
The first sub-unit will consist of four labs and focus on how DC electricity is measured in terms of use (kwh) along with its flow through "basic" series and parallel circuits. During this part of the sub-unit students will have the opportunity to explore their personal and family use of non-renewable, fossil fuel generated electrical energy (electricity) and the resulting "carbon footprint" and other environmental hazards created through the generation of electricity from fossil fuels. Prior to the first lab for this sub-unit students will have had numerous lectures covering "electrostatics" and "electric fields" which includes: electrical forces, charge, Coulomb's Law, electric fields and lines, electric potential difference and energy, and finally the flow of charge and electric current. This unit's lecture material will cover electric resistance, Ohm's Law, AC and DC electricity and finally electric circuits both series and parallel.
The first four labs are "cook book" type labs because students are reinforcing lecture topic concepts and physics theories while learning how to use a multimeter to measure voltage, resistance, and current in a simple circuit. These first four labs are pivotal for student success in the entire curricular unit. I have designed a simple "Physics Experiment Board" which students will use for these labs. All of the equipment for these labs can be purchased from RadioShack® or a similar store such as Fry's Electronics®. The equipment consists of the following:
Physics Experiment Board, Single "D" Battery Holder, Dual "D" Battery Holder,
Two "D" Batteries, Assorted colored jumper leads, Digital Multimeter
I designed the "Physics Experiment Board" using a simple rectangular "grid style pc-board" available from RadioShack® and attaching three light bulbs and six resistors to the board using small, nuts, bolts, and washers. The "bulbs" are small, screw base type, 2.47 V light bulbs attached to the board with light bulb sockets and the resistors are attached to the board by small screws with the posts sticking up about a quarter inch above the board which makes it easy for students to connect test leads to the different resistors.
In Lab 1 students will focus on using their multimeters to measure current, voltage and resistance. They will have been exposed to these concepts in lecture and through problems presented using GRR have had the time to practice solving problems calculating current, voltage and resistance. Students will also begin to draw simple schematics of the electrical components they are using such as the battery, light bulb, and resister. An analysis and reflection part of the lab will require students to use their collected data to calculate any combination of voltage, current, or resistance and then use the multimeter to physically check to see if their calculated value was correct. Percent error will be determined or discussed. Ohm's Law will be used extensively for the calculations in these first four labs.
Ohms Law
R = V/I
Where:R = the resistance, measured in Ohms ( Ω )
V = the voltage, measured in volts (V)
I = the current, measured in amperes (A)
In Lab 2 the students will be using the same equipment and physically constructing simple DC "series" circuit using the battery(s), light bulb(s), and resistor(s). Using the rules for simple DC circuits the students will calculate the voltage, resistance, and current at various locations in the circuit. They will then be required to use the multimeter to check their calculated values at specified locations in the circuits. Lab 3 will require the same equipment and students will follow the same procedures as in Lab 2 but this time will be designing, constructing, and testing "parallel" circuits. During lecture and lab investigations students will receive multiple formative assessments so that lesson plans can be adjusted to meet student learning needs. One formative assessment will require each student to write a quiz to assess lecture concepts and equations along with a performance assessment lab to assess whether a classmate understands the basics of calculating and measuring current, resistance, and voltage in a simple DC circuit.
Students will exchange their written and performance assessment quiz with a fellow student. Each student will complete the quiz, and offer suggestions for improving the assessment, and discuss the data collected through the assessments. I use this method of formative assessment because it allows the students to "pair-share" and help each other to truly understand the material. I will choose a couple of the quizzes or questions from many of the quizzes and construct a summative assessment for this first sub-unit. The reason for the use of formative assessments is due to the fact that this first series of four labs forms the bases for all other labs to follow. The fourth and final lab of this sub-unit will require the students to learn how to read and understand the data provided in their family's utility bill and then go online to a site such as PG & E® to calculate their "carbon footprint." This lab will also be supported by lectures which will cover carbon footprint, greenhouse gases, and the revolutionary approach the City of San Jose is taking in becoming the leading "green" city in the nation.
In the second sub-unit students will explore the possibility of replacing a percentage of their fossil fuel generated electricity with renewable, solar generated electricity. One project which will aid students in exploring this replacement involves the design and construction of a small solar powered cell phone charging station and once again, calculating the effect on their "carbon footprint," and benefits to the environment. Included in the second sub-unit of my curricular unit will involve a series of lectures on solar insolation, solar cell design, function, and use, along with supporting labs.
Labs 5 & 6 will be very similar to Labs 1 through 3 but instead of using batteries as the voltage source students will use photovoltaic cells. They will be working outside for this series of labs. As before, numerous formative assessments will be given and lesson plans adjusted based on student needs. The final lab (Lab 7) of this second sub-unit will require students to form into 4 to 5 member engineering teams. Each team will be required to research and design a "working" solar powered charging station which will be able to charge a cell phone or portable music player. Engineering teams will need to prepare a proposal for their charging station which will include a schematic and all needed parts including a cost analysis. A written explanation of how the charger will function and the function of each individual component in the charging station will also need to be included in the proposal. As before, prior to any construction, engineering teams will exchange plans and critique each other's design and written report. After completing the evaluations and adjusting proposals, each team will meet with me for my critique and evaluation of their proposal. After receiving my input the teams will then acquire their parts and begin to construct their working solar powered charging station.
The third and final sub unit will require the students to work in small, engineering teams to demonstrate that solar powered alternatives can be designed and implemented in many situations on the urban high school campus to decrease the schools' "carbon footprint," save money through the use of renewable, solar energy, and have a positive impact on the campus environment. This final sub-unit of my curricular unit will require students to utilize all of their gained knowledge and skills to "problem solve." Critical thinking skills and creativity will be required as this final part of the curricular unit will allow students the opportunity to solve an open ended problem and justify their answer. Students will be divided into groups of 4 or 5 and choose a name for their engineering team. They will be challenged with a problem on campus in which photovoltaic cells can be used or traditional fossil fuel sources for the generation of electricity. Engineering teams will need to evaluate each situation and propose a solution to their problem in the form of a proposal. The formal proposal will include a written report concerning the environmental impact of their choice of energy source, complete costs and parts lists for the project including a time-line for job completion, drawings, diagrams, and schematics as needed. Each engineering team will present their proposal along with a small working model to the entire class who will serve in the capacity of the client. Students may use any media source they wish to present their proposal as a means of "selling" their ideas. Three examples of the "real life" problems are provided below:
Example 1: From Overfelt's Gardening Club to the Physics Club;
Congratulations!
We, the William C. Overfelt's Garden Club have recently completed our "urban" flower garden featuring only California native plants and trees. Due to the popularity of the garden and the beautiful summer evenings we would like to have installed lighting along the garden path so that the community could walk the gardens after dark. Our Club would like the Newtonians (Overfelt's Physics Club) to provide us with an estimate as to the cost of installing and maintaining such a system. Please remember that the Garden Club is "environmentally friendly" and would prefer to use a renewable energy source such as "solar power" if cost effective. We have attached a sketch of the gardens for your convenience and would like to have a cost estimate and a small working model within two weeks from today's date.
Sincerely;
Veronica Aguirre
Garden Club President
Example 2: From Overfelt's Athletic Department to the Physics Club;
Dear Newtonians (Overfelt's Physics Club);
The Athletic Department is currently planning on constructing a new, "snack shack" to be located on the far west corner of the field. This snack shack will require interior and exterior lighting, and two electrical outlets inside the snack shack to operate a large crock pot, two-50 cup coffee makers, and a handheld radio charging station. Because this new snack shack will only be used during regular season football, softball and soccer games, we would like to explore alternative energy sources to power this facility.
Please develop an alternative or "green" energy plan for us to consider. We would also like a small, model if possible to better help us understand and evaluate your system to confirm that it will meets our needs and be cost effective in maintenance. We look forward to meeting with you in the next two weeks from today's date and are very excited about the prospect of including some type of "green" technology in our program.
Sincerely;
Mark Delgado
William C. Overfelt
Athletics Director
Example 3: From Overfelt's Administration to the Physics Club;
Dear Newtonians (Overfelt's Physics Club);
As you are aware we had a small fire in the custodial building in early May. The fire was localized to the area which housed our golf carts, used for supervision, and the charging transformers for each cart. By October all repairs will have been made to the building and replacement golf carts will be arriving as we lost four in the fire. I am contacting you because of a conversation I had with your Club Advisor, Mr. Barrientez. He spoke very highly of your club and suggested that I should solicit assistance from your club for ideas to the following problem.
The charging transformers for the golf carts will be located in the same building as before, but many times the carts are returned to the building very late and do not get completely charged or charged at all if the custodians are running late. During the day it is not uncommon for many of the carts to just sit in front of the Administration building for hours until needed. A few of the carts may be used all day and have the batteries almost completely drained, but do not fully charge when returned so late in the evening. Thus, my question to you is, "can you devise a charging system using solar generated electricity which can be mounted on top of the Administration building and charge the golf carts while they are not being used?" Thank you in advance for your assistance. If possible could you please have a design, cost quote, etc. available for presentation along with some type of small working model or prototype in the next few weeks?
Sincerely;
Melissa Cortez
Associate Principal
Facilities and Maintenance
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