Discovering Solar Energy
Lesson 5 of 7
Objective: SWBAT explain how a solar panel works and will determine the energy converted in a solar panel.
I start my formative assessment with a class discussion. The discussion is conversational in nature because I want to determine the background knowledge of the students. My goal is to zing their memories and give them anticipatory ideas to be discussed later. I am deliberate in my language as I use vocabulary that will come up later in the lesson.
I begin with a discussion strategy in which I use lap white boards. Groups of students respond to questions on the white board. Voulunteers go to the front of the room and share. I like this strategy because there is a sense of competition that helps keep the students interested in the discussion.
I ask students to respond to one question at a time. I ask, "What is solar energy?", "How does solar energy work?", "What do you own that uses solar energy?" Before students write a final answer they have to discuss their answers together. To support their conversations I use sentence stems to promote conversations. I teach the difference between reporting information and discussing information.
I use Blooms Question Stems (Haywood County School, N.C.) including, "I know that too. I learned in...." "That reminds me....." " I have had a similar experience....".
Students may know more than one another. Students use the accountable talk prompts, "That's interesting. How do you know that?" and, "I had no idea. Tell me more of what you know."
Students write answers to the questions on a lap white board. This allows a visual everyone in the class can see. I respond to the questions by asking the students to look for patterns. If all of the students wrote "Calculators" for the second question, I'll ask if anyone can think of where there are solar panels in other places. We discuss how the department of transportation uses solar powered speed limit indicators. I usually have a student or two use the word photovoltaic. I ask if anyone else has heard the word. There is some discussion about electricity. The students may bring up volts or watts. My students have been taught my lesson, I use my lesson, Measuring Kilowatts and have some background information. I ask them to open their notebooks to the Kilowatt section to review the concepts. In the video below the groups are sharing their white board answers.
Most of my students use solar calculators and think they understand solar energy. I ask students, "How does solar energy work?" There will be silly and downright weird answers as to how solar energy works. I resist the urge to direct teach concepts and instead list the misconceptions on a white board or Chart paper. When they get an idea incorrect, I exclaim, "Wow! That seems like it makes sense. Does anyone else believe that? Interesting." This is a misconception and we'll talk about it during the lesson." As you continue in the unit, return to this board as the student knowledge base grows. Misconceptions can be very hard to break and it is important to reiterate correct information. Solar Energy Net created a handy list of the top five misconceptions in solar energy.
Students now have a working knowledge of solar vocabulary. Now it is time for them to create a conceptual model of solar photovoltaic energy. The first task is to ask how photovoltaic cells work. To teach this I use two You Tube Videos. The first, How Solar Panels Work is a cartoon featuring Frank the Photon. The second is called From Solar Energy to Electricity. I use it because it uses the same information from How Solar Panels Work and builds on it with scientific information that is easy to digest with the back ground of the first movie.
Before the students begin watching the movies I explain that their assignment is to make a drawing of how a solar panel works. I begin with a Vocabulary Dig strategy. My intention is to have the students watch the movies the first time to record vocabulary words from the movies. After the movie is over, students share their vocabulary words. Every person at the table will have the same list of words. These words will be used to label their drawings.
My strategy is to ask students to make a conceptual model of a photovoltaic cell and annotate it. I show the movies again to repeat the concepts. After the movies are over, I ask students to use the vocabulary list we made to label their drawings. I explain that they can draw it how they understand it. It is not necessary to copy the image from the movie. It is surprising how many students use the Frank the Photon from How Solar Panels Work in their drawings. The cartoon helps make the information stick.
Solar Lab Test
In this lab the student will record the number of volts produced by a solar photovoltaic cell. I use the Snap Circuit Alternative Energy kit. There is a handy teacher's guide that helps you snap the solar panel to the voltmeter.
We want to test a solar panel and I want the class to design the lab. I show them the panel and the voltmeter and demonstrate how it works. I use the mini white board and ask kids, What do you think would be a good problem to solve? Students suggest we take the panels outside. I ask where we might also test it. They suggest under a table or in a closet. I use a light meter application to quantify the light.
Students collect and record data. Time is an issue in most experiments and I always get questions about how much time to let it work. I ask, "Why would the time probably not matter?" This leads to a review discussion about the nature of solar panels.
When all the data is collected, my strategy is called One Sentence Conclusion Summary. Students explain what happened in the experiment by explaining the differences between the three different trials.
The purpose of the investigation is a means to an end. My intention is to offer students a reference to use to support a position. My next strategy is Write to Learn. The question they need to respond to is, "Is Solar Power the energy of our future?" They must use information and vocabulary words from the movies as well as data from their investigation to support their answer.
In the movie below I've shared some samples of the drawing and of the summary answering the question, "Is solar energy the energy of the future?" It is interesting to see how the students drew different looking models.