In today's lesson, students learn about electric potential, voltage and current. This builds off the previous lessonwhich was about electric fields that display electric potentials. So that this new knowledge is built off of real-life experience, students build simple circuits and define the parts of the circuit on a drawing.
Since voltage is an electric potential due to electric fields, the performance standards HS-PS3-5: Develop and use a model of two objects interacting through electric or magnetic fields to illustrate the forces between objects and the changes in energy of the objects due to the interaction. Also, students build virtual circuits which applies HS-PS3-3: Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy. Science Practice 2: Developing and using models and Science Practice 8: Obtaining, evaluating, and communicating information as students represent their circuits using schematic diagrams are also applied.
In the previous lesson, Electric Field Lines, students were asked to take a picture of their electric breaker panels in their homes or apartments. All homes are required to have access to their panels, and kids should know where it is. The purpose of this activity is to get students thinking about electric circuits; what better way to do this than make observations about an electric component central to our household circuits. As much as possible, it is important to ground the physics concepts in real life and everyday examples.
I engage students in a Q&A, seen on the video Student Pictures of Breaker Panel to find out what they learned. I call on individual students to share what they learned, what they know and questions they have. A few students stand and share their information, e.g. Student Work on Breaker Panel, before we move onto the 10 minute task where students build and draw a simple circuit.
For this lesson, students build a simple circuit with a battery, light bulb, switch and wires. Then they draw a picture of this simple circuit with schematic symbols. I display the 10 Minute Task - Make and Draw a Circuit power point and hand out the Circuit Diagram worksheet and supplies to students in groups of 2-3. They collect their supplies and most groups have a working circuit within a few minutes. They spend the rest of the time to complete the handout. They draw the circuit two times, once as a true-to-life picture and once in schematic form. The purpose of this is to lead students to their own conclusion that a circuit schematic is a much easier way to visually represent a circuit. It is a student-centered activity that also trains them in how to create simple circuit schematics. Students figure it out on their own with the given resources.
Students also have to answer some questions on the hand out. These questions deal with common misconceptions about circuits that I find students have. For example, they have to figure out if the color of the wire matters, what is an "open" or "closed" circuit and what are the minimum components required to operate a circuit.
It is usually beneficial to start with concrete activities and concepts and then move into the abstract. With this activity, students get hands-on experience of how a circuit operates. In the next section, students learn the vocabulary words: electric potential, voltage and current.
The last activity is to take all of these real-life applications and give it some structure. I present the Electric Potential Power Point to the students. Students are to write this information in their notebooks as I go through the presentation.
The lecture starts with electric potential which is related to the electric field lines from the previous lesson. From electric potential comes the idea of voltage, which students are familiar with in every day life as they deal with batteries, wall outlets and other electrical components. To reinforce and connect the definition of volt with what they know, I show pictures of the objects they know deal with voltage. There are four, multiple-choice questions about voltage in the power point. I display a question, wait a minute for students to read and comtemplate the answer. Then I call on a random student to answer it.
We move onto definitions and diagrams on the simple circuit. Students get several definitions which include: circuit, current, load, resistance, switch and power supply. Then I present the common analogy between water in pipes and electric circuits. Slide 22 shows a list of several parts of an electric circuit (this slide has animations do not work in preview mode, download the power point for full functionality). From this list, students are to think of an analogy to water going through pipes or a hose. It is a think-pair-share activity where I give students one minute to write their answers on a small white board, as seen on the Water Analogy Video. At the end of one minute, I call on groups to supply their analogy to each of the terms on the power point.
The last slide is an exit slip. With their notebooks closed, students are to write the answers on a blank piece of paper. First they draw two schematics. One is a voltage supply and 2 light bulbs in series. The next is a battery, a light bulb and a switch. Then they write down the water analogy for current, voltage and wires. I collect this exit slip and assess it for student understanding.