This is an inquiry-based electricity unit that teaches students about DC series, parallel and compound circuits. Throughout the unit students construct various circuits and observe the values for voltage and current at each position. The goal is that they construct their own understanding of how voltage, current and resistance are determined based on the data they collect and the guided questions they answer. Each day is meant to take 60-90 minutes and includes a student worksheet and usually a corresponding PowerPoint for direct instruction and review. The lessons were designed for students to work in groups with very little direct instruction. If the materials are not available these labs could also be performed using a computer and one of the many circuit simulations available such as PhET's Circuit Construction Kit - DC Virtual Lab. There are a total of eleven separate lessons. The lessons were meant to be taught in order however, several lessons could be modified if less time was available for your students.
For the teacher there is a brief overview of each day’s lesson, a summary of learning outcomes broken down by each day, answer keys, a few review activities and over 80 multiple choice and short answer questions that could be used for smaller quizzes or a big unit exam. The textbook used with this unit originally was Conceptual Physics by Paul Hewitt, but the reading questions could be answered by using most physics textbooks or online at an appropriate website.
Materials Needed Per Group for Investigations
1. 3 miniature light bulbs and receptacles
2. 12 alligator clips/cords
3. 3 D-cell batteries and holders
4. DC ammeter or multimeter
5. DC voltmeter or multimeter
7. various resistors
8. 6V or 9V battery (depends on resistance of resistors used)
All documents are word documents so they can be altered or improved. It also includes brief PowerPoint slideshows to accompany the worksheets which can also be altered.
Day 1 Batteries in Series and Parallel
Students build three circuits to compare batteries in series and parallel and to get accustomed to building circuits from circuit diagrams.
Day 2 Voltage of Batteries and Bulbs in Series
Students connect three D-cell batteries in series with a light bulb and then add two more lightbulbs in series. With each new circuit they measure the voltage across the batteries and light bulbs with a voltmeter.
Day 3 Current in Series Circuits
Students again connect three D-cell batteries in series with a light bulb and then add two more lightbulbs in series. This time they measure both voltage and current for each circuit they build.
Day 4 Ohm’s Law
Students use the data measured for voltage and current in the previous activity to calculate the equivalent resistance of each circuit using Ohm’s law. The students then graph voltage vs current and # of bulbs vs current to see the relationships in Ohm’s law. Then the teacher defines Ohm’s law and the students calculate the resistance of each circuit they previously built.
Day 5 Resistors
Students are introduced to resistors and then they use different resistors to see what happens to bulb brightness, voltage, current and equivalent resistance as the resistance of a circuit is increased.
Day 6 Solving Series Circuits
Students summarize all of their observations and then begin to mathematically solve the voltage, current and resistance of different series circuits.
Day 7 Voltage and Current in Parallel Circuits
Students connect three D-cell batteries in series with a light bulb and then add two more lightbulbs in parallel to explore parallel circuits. They measure both voltage and current for each circuit they build at every point.
Day 8 Solving Parallel Circuits
Students begin to assemble all of their observations in order to begin solving parallel circuits. There are guided practice problems and then several problems that can be done individually or in groups. The last page is a table that has students summarize the rules and observations for series and parallel circuits.
Day 9 Investigating a Compound Circuit
Students assemble a three-bulb circuit where two bulbs are in parallel and then connected in series with a third bulb. They initially make some predictions and then build the circuit and measure the voltage and current at each location.
Day 10 Solving Compound Circuits
Students begin solving compound circuits. There are two different circuits to solve and each question is in order of the sequence they would have to follow to solve each circuit.
Day 11 6-Bulb Circuit (optional)
Students assemble a 6-bulb compound circuit. They initially make some predictions and then build the circuit and measure the voltage and current at each location. They then try to understand their observations based on the what they have learned so far.