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EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle 1. Topic of the lesson Applications of series and parallel electrical circuits This lesson will focus on the knowledge about parallel and series circuits gained in the lesson before. The students will review the relationship between currency, voltage and resistance in complex circuits and learn about applications such as the current and voltage divider. 2. Class The lesson plan is taken from a unit about the concept of the electrical resistance in physics. It is designed for an eleventh grade physics classroom. The students are familiar with the basic concepts about electricity, complex circuits and have profound knowledge about the mathematical techniques such as proportionality and anti-proportionality that will be used during the lesson. 3. Standards The students will be measuring current, voltage and resistance in series and parallel electrical circuits with an analog and digital multimeter in order to record the information. (Standards P-1.3 and P-4.4) Working with voltage sources and the components of electrical circuits it is important for the students to develop an understanding of how to work with electric instruments safely. (Standard P-1.2) Organization and interpretation of the collected data using tables, models and formulas will be important in order to calculate the quantities of current and voltage in the overall circuits and different branches using Ohm's law. (Standards P-1.5 and P-4.5) In addition to that the students will present their results to their groups and or the class. They will have to defend their conclusion talking about advantages and disadvantages (Standard P-1.9) 1/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle 4. Objectives • Students should be able to calculate electrical resistances, currents and voltages in the circuits using Ohm's law. • Students should be able to apply their knowledge about parallel and series circuits to more complex circuits that include branches of both kinds of circuits. • Students should be able to use scientific apparatuses safely. • Students should be able to set up, execute experiments and draw schematic circuit diagrams of complex circuits • Students should be able to analyze, evaluate and interpret the data afterwards. • Students should be able to present their results on a transparency in class • Students should be able to communicate their knowledge and understanding of circuits with their partners, groups and the class. • Students should be able to develop further social competences. They see the importance of individual effort during group work and respect each other’s results. They also engage actively in classroom discussions. 5. Context The present unit is about the electrical resistance. Its definition was introduced in the first lesson: R:=U/I (U is the voltage, I the current and R is the resistance) Characteristics of different conductors and resistors have been recorded in student-focused experiments using simple circuits. The students have become familiar with the use of measuring devices such as volt- and ampere-meter and have used them throughout the unit. The relevance and importance of the subject of this unit has been pointed out talking about energy factors of light bulbs and everyday examples such as the Christmas light set. The previous lesson supplied the students with the general knowledge about parallel and series circuits. Today’s lesson will address this knowledge and will focus on the discussion of voltage and current dividers in different circuits. Including the these two very important tools in different circuits will deepen the students knowledge and help them to understand the implementation of the physics they learn in school into their life’s. Voltage and current dividers are used in dimmers and many other electronic devices. The students will learn how gather certain information out of given material, present it to 2/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle their peers and apply in a more complex circuit. They will see that knowing about a small number of laws and models provides them with enough information to solve very complex problems if only they address the problems in a structured an organized way. To achieve the goal they need to work together in groups with everyone being accountable for the group results. They will share their knowledge with their partner and listen to his or her knowledge in order to complete the task. This way of addressing a physical subject focuses on more than just the physical data and results. The students learn to work together in teams, each one working on one specific part of the problem and then after bringing it all together finish the task together. This social component is important in order to develop scientific activity and understanding. Presenting and defending their own work is another important aspect of scientific research and will -together with the above mentioned aspects- enable the students to engage actively in teamwork in and outside of science. The scientific aspect is still very important and by the end of the unit the students will be able to apply their knowledge not only to actively engage in global issues such as energy saving but also to their everyday life which includes devices such as dynamos on bikes, dimmable lamps. The knowledge about voltage and current dividers will enable them to use electrical devices more safely now knowing how to divide currents and voltages into smaller portions. 6. Materials Items per group - Voltage source or a sufficient amount of batteries (6V) - a few wires or electronic snapkits with resistors and sockets for the batteries - resistors different quantities (at least 40 and 80Ω) and a potentiometer - diode - a volt- and ampere-meter or a multimeter (analog or digital) - transparencies and pen or big sheets of paper and markers Items per student - worksheet with two problems (addendum 1) - Handout for the assessment center (addendum 2) - Material for the different components (addendum 3-5) 3/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle 7. Instructional Sequence Time in Min Section Methods media Planned process and activities . 10 Introduction Teacher (T) picks up the subject of the last lesson up Frontal “Recapitulate the last lesson and the homework. Write impulse down any question you have but also be prepared to answer questions” T explains the carousel method - Students (S) are numbered off with 1 and 2 (so that Frontal half the class is 1and half the class is 2) instruction - S with number 1 build a circle face outwards - S with number 2 build a circle around the inner circle (face inwards) each matching up with a partner from the inside - Inner circle take the role of the teacher, outer circle that of the student asking questions - After 5 minutes outer circles rotates 2 students to the right and roles are changes 10 Review and Students ask the ‘teacher-students’ questions, ‘teachers’ Recapitulation try to answer. Carousel After the change of roles the former ‘teachers’ have the chance to ask further unanswered questions and the former students have the chance to test their understanding trying to answer the questions 10 Review S get two problems to work on for 5 minutes (see Think- addendum 1) 15 S share their results with partner for 5 minutes Pair-Share Collection and Teacher collects students’ results at the blackboard and Teacher confirmation goes over unanswered questions together with the class guided Blackboard 4/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle 5 Stating the problem T introduces the problem: “Browder Electronics Co Inc down on Wayne Street is hiring new employers and you all were invited for an assessment center. You will be working on a project in groups of three. The project can be divided in three major Impulse Frontal instructions components and each of you will be responsible for one of the three. The company wants to find out more about your individual skills but also about your ability to work in different groups. You will therefore be put in groups of four working on one of the components. After that you will get back to your initial group and explain your component to them since you all should know everything about the project. You will then put the components together and present your results to the jury. Each of you should be able to present your final project next lesson and should be prepared to defend it.” The problem with instructions will be distributed to the students and introduced by the teacher (problem see addendum 2) 40 Laboratory OHP or Powerpoint Slide Students in the home groups make sure they understand Jigsaw what they have to do and then get together in the expert Home group groups of four. work The expert groups work on the material and do some experiments about the component they are dealing with It is important that they know how their component works, Expert group and how it might be used in the circuit. work (materials for the components see addendum 3-5) The home groups get back together and explain each other the function and the mode of operation of their component. Home group Groups come up with a circuit that satisfies the requests work by putting the current and voltage divider as well as the 5/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle potentiometer in the right spots in the circuit. S verify their results measuring the important quantities in their circuits. The students will present their work in the next lesson giving each group enough time to present and defend their results and to answer questions 8. Assessment In the beginning the students will be asked to review the material of the previous lesson and to think of any questions they still have about parallel and series circuits and the specific relationship. They should also be prepared to answer questions about the content. During the carousel the half of the students will take the role of a student asking questions and the other half will take the role of the teacher trying to answer the questions. After a few minutes the carousel ‘moves’ and the roles change. This is the chance to ask unanswered questions and to see how good one’s understanding of the subject is. The students will then be given two problems; one about a series circuit and one about a parallel circuit. Everyone gets 5 minutes to think about and to solve the problem. After that the students share their results with a partner. The final solution will then be written down on the board. Any unanswered questions about the subject related to the general conceptions of series and parallel circuits will be address in class at this point. The detailed review of the content is to secure a profound base for the following jigsaw and is also a preparation for the quiz the students will be given at the beginning of the next lesson. The jigsaw includes experiments measuring voltage and current in circuits. The experiments main purposes are to collect the data that can be used to conclude the general formula of a voltage or current divider and to come up with possible solutions for the main problem. The material for the expert groups includes questions and assignments that will guide the student through the activity helping them to understand the subject matter. The presentation of the results will take place in the next lesson. 6/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle 9. References National Science Education Standards (1996) Retrieved August 23, 2009, from The National Academies Press Web Site: http://www.nap.edu/openbook.php?record_id=4962 South Carolina Curriculum Standards (2005) Retrieved August 23, 2009, from South Carolina Department of Education Web Site: http://ed.sc.gov/agency/Standards-and- Learning/AcademicStandards/old/cso/standards/science/ All About Circuits. (n.d.) Retrieved September 30, 2009 from http://www.allaboutcircuits.com 10. Addendum 10.1. Worksheet 7/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle 10.2 Assignment for the jigsaw Browder Electronics Co Inc Assessment Center You are given a 6V battery, two resistors, a potentiometer and a diode.The diode holds only 2V and the current through the diode should be variable from 0 to 50mA. The three major components of your circuit will be a voltage divider, a current divider and a potentiometer. The purpose of the expert groups is to go through the material for one of the components. You will be given some background information that will allow you understand the principle and if necessary to develop a formula. You will then be asked to collect data in an experiment to verify your formula and to understand how to implement the component in a circuit. You will present your findings to your home group and you and your partners will then work on putting the requested circuit together: 1. Discuss how to put the three components together in one circuit 2. Draw a schematic circuit diagram. 3. Calculate the quantity of the two resistors in your circuit 4. Put the circuits together using the material that was given to you 5. Verify your results measuring the important voltages and currents using the potentiometer to vary the current through the diode. 6. Make sure everyone in your group understands the circuit and can present and explain the major components. 7. Prepare a transparency to help you present your results 8/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle 10.3 Material for the expert group ‘voltage divider’ The voltage divider The schematic diagram above depicts the simplest two resistor voltage divider. It includes two resistors R1 and R2 in a series circuit. Build a series circuit with any two resistors and a battery with Uin=6V. Measure current and voltage at the important points in the circuit and fill in the blanks in the following table. Voltage U in V Current I in A Resistance R in Ω R1 R2 Rtotal 6V Verify your results by calculating the quantities with Ohm’s law: Voltage U in V Current I in A Resistance R in Ω R1 R2 Rtotal 6V Explain possible offsets between your measurements and calculations. __________________________________________________ 9/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle __________________________________________________ __________________________________________________ Now look at the relationship of the voltage drop and the resistance. What do you notice? Hint: If you don’t see any connection yet calculate the ration of the two resistors and compare it with the ratio of the voltage drops. __________________________________________________ __________________________________________________ Imagine you have two unknown resistors R1 and R2 what is the formula for the voltage Uout if your initial voltage is Uin? (Use Ohm’s law and the knowledge gained in the experiment above) This result supplies us with a very important tool and explains the name voltage divider. It refers to the fact that we can partition a voltage among components in a circuit. Using two or more resistors in a series circuits allows us to divide the voltage at each resistor into portions we can control with the choice of the resistors. We can use it to supply a second circuit with a different voltage than that of an available battery or power supply. The larger the resistor the larger is the voltage drop over the resistor. Hint: When you are back in your home group apply the knowledge about the voltage divider to the requested voltages.The knowledge about the voltage and the maximum current allows you to calculate the total resistance. 10/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle 10.4 Material for the expert group ‘current divider’ The current divider The schematic diagram above depicts the simplest two resistor current divider. It includes two resistors R1 and R2 in a parallel circuit. Build a parallel circuit with any two resistors and a battery with Uin=6V. Measure current and voltage at the important points in the circuit and fill in the blanks in the following table. Voltage U in V Current I in A Resistance R in Ω R1 R2 Rtotal 6V Verify your results by calculating the quantities with Ohm’s law: Voltage U in V Current I in A Resistance R in Ω R1 R2 Rtotal 6V Explain possible offsets between your measurements and calculations. __________________________________________________ __________________________________________________ _________________________________________________ 11/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle Now look at the relationship of the current going through a resistor and the resistor. What do you notice? Hint: If you don’t see any connection yet try to fill in the blank in the following sentence and calculate the ration of the two resistors and compare it with the ratio of the branch currents. (The greater the resistance the ____________ the current) __________________________________________________ __________________________________________________ Imagine you have two unknown resistors R1 and R2 what is the formula for the voltage I1 if your initial current is Iin? (Use Ohm’s law and the knowledge gained in the experiment above) This result supplies us with a very important tool and explains the name current divider. It refers to the fact that we can partition a current among components in a circuit. Using two or more resistors in a parallel circuit allows us to divide the current at each resistor into portions we can control with the choice of the resistors. We can use it to supply a second circuit with a different current than that of an available battery or power supply. The larger the resistor the smaller is the current through the resistor. Hint: When you are back in your home group apply the knowledge about the current divider to the variable current. You need to implement the potentiometer into your current divider. 12/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle 10.5 Material for the expert group ‘potentiometer’ The potentiometer A potentiometer is a resistor that can be adjusted. The easiest set-up of a potentiometer is a long piece of wire or pencil “lead”connected to a battery. Adjusting the position of one of the connection to the multimeter changes the resistance. The principle of the potentiometer is based on three different ‘terminals’ (wires). One is connected to a battery, a second one is connected to ground (no voltage or resistance) and the third is variable on a resistive material, which has a low resistance at one end with an increasing resistance towards the other end. The position of this wire can be changed and thus the resistance is changed. Changing the resistance one can control the current running through a circuit. Build the circuit as shown above and measure the resistance at more than 2 positions verifying the variable resistance. Position 1 2 3 4 Resistance Determine the range of your ‘potentiometer’: _____________________________________ You are given a potentiometer that can be adjusted from 0 to 10kΩ. Verify the range of the potentiometer using your multimeter and try the different positions of the potentiometer making yourself familiar with the configuration. Now build a series circuit with a resistor (R1=100Ω), the potentiometer and a 6V battery. Measure the current and voltage in the circuit as you change the resistance of the potentiometer. Potentiometer-resistance in Ω 13/14 EDSE 732 SECONDARY SCIENCE METHODS 4/17/10 Lesson Plan – Cooperative Learning Moritz Huegle Total resistance in Ω Total current in A Total voltage in V What is the relationship between the resistance of the potentiometer and the current in the circuit? Now put the resistor, the potentiometer and the 6V battery in a parallel circuit. Measure the current and voltage in the circuit and in the different branches as you again change the resistance of the potentiometer. Potentiometer-resistance in Ω Total resistance in Ω Total voltage in V Total current in A Resistor current in A Potentiometer current in A What is the relationship between the resistance of the potentiometer and the current through the potentiometer? Hint: When you are back in your home-group apply your knowledge about the potentiometer and how it works in the two circuits to the fix current you have running through the main circuit which is supplied by a 6V battery. 14/14