Lesson Plan – Current Electricity
QED 521: Microteaching & Lesson Plan Assignment
submitted as a requirement for the
Postgraduate Diploma in Education (Secondary)
by
Ho Chien Meng Simon (S8016856Z)
Final Lesson Plan
Lecturer: A/Prof Yap Kueh Chin
Assessor: A/Prof Paul Lee
Submitted on: October 2005
Lesson PlanDuration: 2 periods (70 mins)
Title of Lesson: Current Electricity
Venue: Classroom
Sub-Topic:Potential Difference and Electromotive Force
Class :Secondary 4 Express (Pure Physics)
Lesson Objectives:
At the end of the lesson, the students should be able to:
(a)define the electromotive force (e.m.f) of a cell (source) as the work done by a source in driving one unit of charge around a complete circuit;
(b)calculate the total e.m.f where several sources are arranged in series or parallel;
(c)define the potential difference (p.d) across a component in a circuit as the work done to drive a unit charge through the component;
(d)state the S.I. units for e.m.f and p.d is volts (V);
(e)state that we measure the e.m.f and p.d. in circuits using a voltmeter;
(f)state that the total e.m.f is equal to the sum of the p.d across all the components in a complete circuit
without reference to their textbooks or notes.
Prior Knowledge/Pre-requisites:
(a)Students should be able to define the concepts of current, of conventional current and of electron flow.
(b)Students should be able to state the definition of current as the net charge flowing through a conductor per unit time.
(c)Students should be familiar with the water-pressure analogy for current flow from the previous lesson.
(d)Students should be able to distinguish between a unit charge and one electron.
New Concepts/Terms:
Electromotive force (e.m.f), potential difference (p.d), Volt (V)
Learning Aids and Resources:
IT:(i)Crocodile Physics simulation (Appendix 6)
(ii)Visualiser
Teacher Demonstration: 1 DC microammeter, 1 aluminum plates, 1 copper plate (both the size of a human palm), 2 electrical lead wires with crocodile clips at both ends
Instructional Aids:(i) Powerpoint® Slides (Appendix 1)
(ii)OHT (Appendix 2)
Worksheet: (i)for student hands-on investigation (Appendix 3)
(ii)for homework (Appendix 4)
Hands-on (per group):3 batteries (each with individual holders), wires with crocodile clips at one end, 2 light bulbs with holders, 1 switch, 1 voltmeter
Lesson Development:
Recap:
(i)Recall the concepts of current and how we can measure current using an ammeter, of conventional current and of electron flow in a closed circuit.
Set Induction:
(ii)Pose a question to the students: Must we always use a battery to set up a current in a circuit?
(iii)Execute teacher demonstration. The students should realize that a current is flowing through the circuit even though there is no battery!
Lesson Development:
(iv)Introduce the concept of electromotive force (e.m.f) as what causes a current to flow.
(v)Recap the water-pressure analogy. Relate e.m.f to the pressure difference in the water column that causes the water to flow in the tubing. State that a battery (or any other source, such as my hands in the demonstration) creates an e.m.f.
(vi)State the definition that e.m.f = work done / charge. Units = volt.
(vii)Introduce the concept of potential difference (p.d) across a component.
(viii)State the definition that p.d = work done / charge. Units = volt.
(ix)Using the water-pressure analogy, relate how it is p.d that causes current to flow through a component in a circuit. State where the analogy breaks down.
(x)Explain to the students how e.m.f and p.d are different.
(xi)Introduce the voltmeter and state how to use it to measure e.m.f and p.d.
(xii)Students carry out guided investigations using the electrical components in groups of 4.
(xiii)Discuss with students the following observations:
- The total e.m.f of batteries (sources) placed in series is the sum of the individual e.m.f.
- The total e.m.f of batteries (sources) placed in parallel is the individual e.m.f.
- The total e.m.f of the sources in a circuit is equal to the sum of the p.d across all the components in a circuit.
(xiv)Use the crocodile simulation to explain to students the danger of reversing the polarity of one of the batteries in parallel arrangement.
Student Participation:
(i)This is a student-centered lesson whereby the students worked in groups of 4 for a quarter of the lesson on hands-on electrical circuits.
(ii)Use of demonstration to pique their interest and create cognitive disequilibrium to aid their accommodation of new concepts and knowledge.
Collaborative Learning and Discussion:
Class Discussion is carried out after the hands-on activity to consolidate and confirm students’ observations and learning points.
IT
Use of Crocodile simulation to demonstrate to students the danger of short-circuiting batteries together.
Closure:
(xv)Conclude the lesson recapping the definitions of e.m.f and p.d, and pose the question: Can you explain now why birds perching on MRT tracks do not get electrocuted?
Reference:
Paatz, R., Ryder, J., Schwedes, H. & Scott, P. (2004). A case study analysing the process of analogy-based learning in a teaching unit about simple electric circuits. International Journal of Science Education, 26(9), 1065-1081.
Loo W.Y., Loo K.W. and See Toh W.F. (2001), Physics Insights. Singapore: Longman.
The Exploratorium, Hand Battery. Available online:
Time / Activities / Resources / Rationale5 min /
- Greet the class.
- Set up the computer and OHP.
- Introduce objectives of today’s lesson: introduce you to the concepts of what makes current flow.
- Recall what ‘current’ and ‘unit charge’ are and the concepts of current, conventional current and electron flow by eliciting students’ response.
- Pose a question to the students: Must we always use a battery to set up a current in a circuit?
- Solicit their response.
Recall the previous concepts learned.
The question gets the student to think, and may create cognitive disequilibrium to aid accommodation of new knowledge.
5 min /
- Execute teacher demonstration. Use the visualiser (if available) to project the microammeter reading for class to see. If no visualiser is available, get the students in front to report to the class the deflections. (See Appendix 5)
aluminum plate copper plate
- Ask the students what they observed. After the demonstration, discuss with the class that I have set up an electric current without the use of a battery.
- Introduce the concept of electromotive force (e.m.f); i.e. a source (e.g. battery) causes current to flow by setting up and maintaining an e.m.f.
Powerpoint slides / Demonstration is a visual way to create the cognitive disequilibrium. Projection using the visualiser allows whole-class participation.
Use the demonstration to correct misconception that a battery is what causes current to flow. Introduce the scientific conception of e.m.f instead for students accommodation.
7 min /
- Recall the water-pressure analogy used in the last lesson.
- Ask the students a recap question: “Which part of the water circuit is analogous to the battery?” [Water column]
- “How does the water column move the water along the pipes? What is the cause of the force?” [Pressure Difference]
- The e.m.f set up by a source is analogous to the pressure difference (height difference in the water columns) that causes water to flow.
- “Can the moving water do work?” “Where does it get the energy to do work from?” [Yes. From the gravitational potential energy stored in the differential water columns]
- Pressure difference implies potential energy that allows the water to do work as it flows through the tubing. Analogously, e.m.f set up by a source implies energy (electrical energy).
- State the definition of e.m.f: The e.m.f of a source is the work done by a source in driving a unit charge around a complete circuit.
- Introduce the symbol for e.m.f (), and give the definition in formula.
- Introduce that the unit of e.m.f is volt (V), and define what 1 V is.
- Go through Worked Example 1. Allow students some time to work out the problem themselves.
- Ask simple recall questions:
- What does e.m.f stands for?
- Define the e.m.f of a source for me.
- The standard AA size batteries in the market are marked 1.5 V. Tell me what that means.
Powerpoint slides / TWA model. Using a familiar analogy to make an abstract concept meaningful and accessible to the students.
Direct instruction after analogy has been introduced helps scaffold students’ knowledge.
Formative assessment before moving on.
10 min /
- Introduce the concept of potential difference (p.d) across an electrical component.
- State the definition of p.d: The p.d across a component in a circuit is the work done to drive a unit charge through the component.
- Introduce the symbol for p.d (V), and give the definition in formula.
- Introduce that the unit of p.d is volt (V), and define what 1 V is.
- Relate to the water-pressure analogy. The p.d is analogous to the pressure difference that causes water to flow across the dynamo, doing work.
- Ask the students questions: “Moving water from lower to higher gravitational potential – is work done on or by the water? What about moving water from higher to lower gravitational potential?”
- Moving a charge from higher to lower potential is analogous to water flowing from higher to lower pressure: work is done by the charge/water.
- Moving a charge from lower to higher potential is analogous to pumping water from lower to higher pressure (in tall buildings): work is done on the charge/water.
- State how the water-pressure analogy breaks down: there is pressure difference across every section of the tube, but p.d across sections of the wire is negligible.
- Go through Worked Example 2. Allow students time to work through the example themselves.
- Ask a simple recall question:
- Define for me p.d across a component.
OHT diagram of analogy
Powerpoint slide / Introduction of a new concept helps scaffold students’ knowledge.
TWA model. Use of familiar analogies to make abstract concepts meaningful and accessible to the students.
TWA model. State limitations of analogy to prevent student mapping of irrelevant attributes.
Formative assessment before moving on.
5 min /
- Explain the difference between e.m.f and p.d. The e.m.f is energy supplied by a source to drive a unit current through a circuit; the p.d is the energy converted to other forms as current moves across a component.
- e.m.f: other forms of energy electrical energy
- p.d: electrical energy other forms of energy.
- Get students to peer teach the difference between e.m.f and p.d to their neighbours in their own words. Then get a few to share with the class.
Think-Pair-Share helps students to construct their own understanding.
1 min /
- Get students to collect their apparatus and worksheet for the next section of the lesson.
- Remind students of routine and rules: No taking out of the apparatus until I tell you to do so.
2 min /
- Introduce the voltmeter. Get the students to take out the voltmeter.
- Explain how we use the voltmeter: we measure the e.m.f across a source, or p.d across a component, so we connect a voltmeter across the source or component.
- Like the ammeter, conventional current enters at the red terminal, exits at the black terminal
Powerpoint slide (diagram)
15 min /
- Describe to the students the hands-on activity they will do next.
- Investigation by the students in groups of four. They will set up different circuits and measure the total e.m.f and p.d across different components in the circuit. They will need to record their observations and answer a few simple questions in their groups.
Worksheet (Appendix 3) / Guided-Student Discovery Learning. Let the students discover the relationship between e.m.f and p.d, and how to find total e.m.f.
Learning to teamwork and discussion.
10 min /
- Gather the class for a discussion of the activity and questions in the worksheet. Use Crocodile simulation to assist in the discussion.
- Establish the concept that for batteries (sources) arranged in series, total e.m.f = sum of individual cell’s e.m.f.
- Establish the concept that for batteries (sources) arranged in parallel, total e.m.f = individual e.m.f
- Establish the concept that in any complete circuit, the total e.m.f = sum of p.d across all components in the circuit. Link this to the conservation of energy.
- Go through questions in worksheet.
Whiteboard / Student-centered discussion on their investigation.
Crocodile simulation used here to raise ‘credibility’ of simulation.
Students discover these concepts through the activity themselves.
5 min
(filler) /
- Ask the question: Why didn’t I ask you to investigate the total e.m.f for a circuit where the batteries are in parallel, with one of the batteries’ polarity reversed instead? What would be the total e.m.f in this case?
- Solicit students’ response.
- Demonstrate what happens with the Crocodile simulation.
- Explain what happened: connecting two batteries together causes a very large current to flow in the conducting wires. The batteries heat up and explode.
- Relate to real life: Don’t carry batteries in your pockets with loose change. Don’t use batteries in wet areas etc.
This demonstration can be done safely only with a simulation.
Relating to real life makes the concepts learned more meaningful and concrete for the students.
10 min /
- Recap the learning points of the lesson. As each learning point is flashed, ask the students to define or state the concept learnt.
- Hand out Homework
- Prepare the students for the next lesson on resistance: Why does a large current flow when we conduct two batteries to each other?
- Thank the class.
Homework Worksheet
(Appendix 4) / Summary provides a structure to student learning.
Homework help consolidate learning for students.
Advanced questioning as a teaser for the next lesson.
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Ho Chien Meng Simon