Unit Three Organizer: It s Electromagnetic (Approximate Time: 7.5 weeks)

Transcription

1 The following instructional plan is part of a GaDOE collection of Unit Frameworks, Performance Tasks, examples of Student Work, and Teacher Commentary. Many more GaDOE approved instructional plans are available by using the Search Standards feature located on GeorgiaStandards.Org. OVERVIEW: Unit Three Organizer: It s Electromagnetic (Approximate Time: 7.5 weeks) By the eighth grade, students have had limited exposure to the concepts of electricity and magnetism. It is in 8 th grade physical science that most students will first be exposed to chemistry as the source of the energy that makes electricity, as well as the connected nature of electrical charge and magnetism. This framework is intended to expose students to the basics of charges, electrical flow through circuits, magnetism, and the integration of electromagnetic science into technology. The students will make the connection between electricity, magnetism, and technology through the completion of tasks designed to teach the concepts through hands-on experience. The tasks will take the students from electricity to magnetism by constructing a simple wet cell and battery system, a simple static electric generator, an electromagnet, and culminating in the building of two pieces of technology- a simple computer circuit, and an electrical communication device. By actually building these devices, the students will reinforce classroom instruction and be given an opportunity to demonstrate the level of their understanding of the concepts. STANDARDS ADDRESSED IN THIS UNIT Focus Standard: S8P5. Students will recognize characteristics of gravity, electricity, and magnetism as major kinds of forces acting in nature. b. Demonstrate the advantages and disadvantages of series and parallel circuits and how they transfer energy. c. Investigate and explain that electric currents and magnets can exert force on each other. July 2008 Page 1 of 22

2 Supporting Standards: S8P1. Students will examine the scientific view of the nature of matter. a. Distinguish between atoms and molecules. b. Describe the difference between pure substances (elements and compounds) and mixtures. c. Describe the movement of particles in solids, liquids, gases, and plasmas states. d. Distinguish between physical and chemical properties of matter as physical (i.e., density, melting point, boiling point) or chemical (i.e., reactivity, combustibility). S8P2. Students will be familiar with the forms and transformations of energy. a. Explain energy transformation in terms of the Law of Conservation of Energy. b. Explain the relationship between potential and kinetic energy. c. Compare and contrast the different forms of energy (heat, light, electricity, mechanical motion, sound) and their characteristics. Habits of the Mind S8CS1. Students will explore the importance of curiosity, honesty, openness, and skepticism in science and will exhibit these traits in their own efforts to understand how the world works. a. Understand the importance of and keep honest, clear, and accurate records in science. b. Understand that hypotheses can be valuable even if they turn out not to be completely accurate. S8CS2. Students will use standard safety practices for all classroom laboratory and field investigations. a. Follow correct procedures for use of scientific apparatus. b. Demonstrate appropriate techniques in all laboratory situations. c. Follow correct protocol for identifying and reporting safety problems and violations. S8CS4. Students will use tools and instruments for observing, measuring, and manipulating equipment and materials in scientific activities utilizing safe laboratory procedures. a. Use appropriate technology to store and retrieve scientific information in topical, alphabetical, numerical, and keyword files, and create simple files. b. Use appropriate tools and units for measuring objects and/or substances. c. Learn and use standard safety practices when conducting scientific investigations. July 2008 Page 2 of 22

3 S8CS5. Students will use the ideas of system, model, change, and scale in exploring scientific and technological matters. a. Observe and explain how parts can be related to other parts in a system such as the role of simple machines in complex machines. b. Understand that different models (such as physical replicas, pictures, and analogies) can be used to represent the same thing. S8CS6. Students will communicate scientific ideas and activities clearly. a. Write clear, step-by-step instructions for conducting scientific investigations, operating a piece of equipment, or following a procedure. b. Write for scientific purposes incorporating information from a circle, bar, or line graph, data tables, diagrams, and symbols. c. Organize scientific information in appropriate tables, charts, and graphs, and identify relationships they reveal. S8CS6. Students will question scientific claims and arguments effectively. a. Support statements with facts found in books, articles, and databases, and identify the sources used. b. Identify when comparisons might not be fair because some conditions are different. The Nature of Science S8CS8. Students will be familiar with the characteristics of scientific knowledge and how it is achieved. Students will apply the following to scientific concepts: a. When similar investigations give different results, the scientific challenge is to judge whether the differences are trivial or significant, which often requires further study. Even with similar results, scientists may wait until an investigation has been repeated many times before accepting the results as meaningful. b. When new experimental results are inconsistent with an existing, well-established theory, scientists may pursue further experimentation to determine whether the results are flawed or the theory requires modification. c. As prevailing theories are challenged by new information, scientific knowledge may change. S8CS9. Students will understand the features of the process of scientific inquiry. Students will apply the following to inquiry learning practices: a. Investigations are conducted for different reasons, which include exploring new phenomena, confirming previous results, testing how well a theory predicts, and comparing different theories. Scientific investigations usually involve collecting evidence, reasoning, devising hypotheses, and formulating explanations to make sense of collected evidence. b. Scientific investigations usually involve collecting evidence, reasoning, devising hypotheses, and formulating explanations to make sense of collected evidence. July 2008 Page 3 of 22

4 c. Scientific experiments investigate the effect of one variable on another. All other variables are kept constant. d. Scientists often collaborate to design research. To prevent this bias, scientists conduct independent studies of the same questions. e. Accurate record keeping, data sharing, and replication of results are essential for maintaining an investigator s credibility with other scientists and society. f. Scientists use technology and mathematics to enhance the process of scientific inquiry. ENDURING UNDERSTANDINGS Electricity is a general term used to refer to the presence and/or flow of electrical charges. It is usually associated with the movement or position of those charges. Static electricity is the attractive force between oppositely charged objects due to a buildup of negative charges. Static electricity is nonmoving charges. A wet cell or dry cell can be used to produce electricity through a chemical reaction. A battery is a series of electrical cells. Insulators are poor conductors and resist charge movement while conductors are poor insulators and tend to allow charges to easily move. Closed circuits allow current flow while open circuits do not have an unbroken path for current movement. A series circuit contains only one path for electricity to flow, while a parallel circuit contains more than one path. Parallel circuits are an advantage in that bulbs in parallel will still work if one of the burns out. Magnets can induce electric current and electric current can produce a magnetic field. Magnets can be used to make electricity when needed. Electricity can be used to make a magnet when needed. Electromagnets are used in electric motors to transform electrical energy to mechanical energy. Generators convert mechanical energy to electrical energy. July 2008 Page 4 of 22

5 ESSENTIAL QUESTIONS: How is electricity produced and used? What are the advantages and disadvantages of series and parallel circuits? How are insulators and conductors used in the movement of charges? How is static electricity different from regular electricity? How are parallel and series circuits different and how are they alike? What are the differences between permanent magnets and electromagnets? What are the factors that affect the strength of electromagnets? How are electric motors related to electric generators? In what ways are electromagnets used in modern technology? How are electricity and magnetism used in modern technology? CONCEPTS: Nature of electricity and charge Nature of electric current Differences between direct and alternating current Uses of conductors and insulators in circuits Advantages and disadvantages of series and parallel circuits Nature of magnetism Use of electricity to generate a magnetic field Use of magnets in creating motors and generators July 2008 Page 5 of 22

6 LANGUAGE: Battery Cell Circuit Closed Circuit Conductor Current Dry Cell Electrical Charge Electric Field Electrical Force Electric Motor Electricity Electromagnet Generator Induction Insulator Magnet Magnetic Field Open Circuit Parallel Circuit Permanent Magnet Poles Series Circuit Static Electricity Switch Technology Transformer Volt Voltage Wet Cell MISCONCEPTIONS Electricity is only moving charges. Electrical charge results from the movement of positive and negative charges. Electricity moves like water through a pipe. A cell is the same as a battery. Batteries store electricity. PROPER CONCEPTIONS Electricity describes the charges that result from the movement or positions of electrical charges. Under normal circumstances, positive charges cannot leave an atom. Only the negative charges are able to move. Water flows as a result of gravity. Electricity, being negatively charged, moves away from like charged objects and towards oppositely charged ones. Additionally, the charges require a complete path to flow. A cell is a single unit that produces electrical current through a chemical reaction. A battery is two or more cells connected in series or parallel circuits. A cell or battery may produce electricity from chemicals contained within. Some contain chemical processes that are reversible by recharging them. July 2008 Page 6 of 22

7 Wire must be coiled to produce a magnetic field. Wire must be coiled around and iron core to produce a magnet. Any wire carrying an electric current generates a magnetic field. Coiling the wire increases the field to allow it to be more easily detected. Coiled wire, or any wire carrying an electric current produces a magnetic field. Adding an iron core strengthens and focuses the field. EVIDENCE OF LEARNING: Culminating Activity: GRASPS GOAL: You are working for a government agency that is responsible for encryption and code breaking. Your challenge is to design and build two pieces of technology that incorporate electricity and magnetism. The first is a simple computer using electrical circuits to compute a simple arithmetic problem and to arrive at an answer displayed by an output device. The second is to design a communication device and communicate your findings to your team members in code. ROLE: You are an engineer leading a team made up of your colleagues. You as the team leader will help design and build your devices and communicate with your team members. It is up to you as a team to work well together to design and build the devices, along with your coding system to complete the mission. AUDIENCE: Your team members are depending upon you to solve the problem and communicate the vital information. Watching you will be spies, such as other teams, as well as your teacher. SCENARIO: The devices you build will be examples of technology- the use of scientific knowledge in applications that serve a purpose. Your devices should be tested and refined and be fully functional in the end. Your team is competing with other teams (spies) to be the first to complete the design and build of these critical devices and to complete the mission. PRODUCT: The design of your devices will include many components of the fields of electricity and magnetism. Besides displaying your functional devices, you will produce written reports that include detailed drawings of the parts of the devices and explanations of their functions. You will also make your code available to your teacher, the director of your agency. July 2008 Page 7 of 22

8 Evidence of Scientific Understanding: Computing Device Evidence of Scientific Understanding: Communication Device Organization and Analysis RUBRIC FOR CULMINATING ACTIVITY Exceeds Expectations 4 points The student clearly exhibits understanding of electrical circuits and components in project work and clearly explains same in written report. There is evidence of thorough understanding of all parts and workings of the device. Student demonstrates a thorough understanding of the circuits and components of the device, including explanations of why each part is necessary. The student also explains the coding system and demonstrates understanding of same. Student written report clearly shows how devices were developed and how and why each component is included to aid in function. Report shows how each device functions and includes the descriptions of input and output to computer and the coding system developed for communication. Meets Expectations 3 points The student attempts to explain how and in what manner electricity flows through the device but may not completely explain all components in class or in writing. The student does not exhibit thorough understanding of how the device computes and displays data. Student demonstrates basic knowledge of the communication device, but may not thoroughly explain how and why various components are necessary. Knowledge of coding system is evident, but may not be at expert level. Student recording, organization and analysis of the devices and their development are included in the written report. Results of functions are discussed minimally. Does Not Meet Expectations 2 points The student did not explain how and in what manner electricity flows through device circuits and does not exhibit evidence of understanding of the components of the device. Student does not thoroughly explain the functions of the device or the reasons for inclusion of the components. Evidence does not exist that the student understands or has mastered the code system. Student recording, organization and analysis of the devices is not complete in written report. July 2008 Page 8 of 22

9 Effort and Participation Active student participation was evident throughout the activity. Student interacted with team members and others in a respectful and productive manner. Student participation was evident throughout the activity, but lacked enthusiasm. Student interactions were respectful and not counterproductive. Student did not participate or work in each aspect of this exploration and failed to interact with team members in a positive and encouraging manner. UNIT RESOURCES Electricity Magnetism Motors/Generators Technology July 2008 Page 9 of 22

10 Standards (Content and Characteristics): One Stop Shop For Educators Culminating Activity- Electricity and Magnetism in Technology S8P5. Students will recognize characteristics of gravity, electricity, and magnetism as major kinds of forces acting in nature S8P2. Students will be familiar with the forms and transformations of energy. S8CS1. Students will explore the importance of curiosity, honesty, openness, and skepticism in science and will exhibit these traits in their own efforts to understand how the world works. S8CS2. Students will use standard safety practices for all classroom laboratory and field investigations. S8CS4. Students will use tools and instruments for observing, measuring, and manipulating equipment and materials in scientific activities utilizing safe laboratory procedures. S8CS5. Students will use the ideas of system, model, change, and scale in exploring scientific and technological matters. S8CS6. Students will communicate scientific ideas and activities clearly. S8CS8. Students will be familiar with the characteristics of scientific knowledge and how it is achieved. S8CS9. Students will understand the features of the process of scientific inquiry. Enduring Understanding: Electricity is a general term used to refer to the presence and/or flow of electrical charges. It is usually associated with the movement or position of those charges. Insulators are poor conductors and resist charge movement while conductors are poor insulators and tend to allow charges to easily move. Closed circuits allow current flow while open circuits do not have an unbroken path for current movement. A series circuit contains only one path for electricity to flow, while a parallel circuit contains more than one path. Parallel circuits are an advantage in that bulbs in parallel will still work if one of the burns out. Magnets can induce electric current and electric current can produce a magnetic field. Magnets can be used to make electricity when needed. Electricity can be used to make a magnet when needed. Electromagnets are used in electric motors to transform electrical energy to mechanical energy. July 2008 Page 10 of 22

11 Essential Questions: What are the advantages and disadvantages of series and parallel circuits? How are insulators and conductors used in the movement of charges? How are parallel and series circuits different and how are they alike? What are the differences between permanent magnets and electromagnets? What are the factors that affect the strength of electromagnets? In what ways are electromagnets used in modern technology? How are electricity and magnetism used in modern technology? ADMINISTRATION PROCEDURES Outcome / Performance Expectations: General Teacher Instructions: Each student or team will design and create two pieces of technology incorporating electricity, circuits, and possibly magnetism. The two devices will consist of a simple computer circuit for completing math calculations using the digits 0 and 1. The second device will be a simple communicator using electrical circuits and switches to light bulbs and/or ring bells to communicate via code (a telegraph) as well as a code system by which to communicate via the device. PART ONE- Simple Computer Build a circuit using 2 dry cell flashlight batteries, wire, clips, switches, and bulbs as shown below. You may want to have the students build one circuit with a switch labeled 1 and 0 to begin with, and ask them to think of ways to use this circuit in conjunction with other circuits to do math problems. This adds an inquiry element to the activity and will open the door to some surprising ideas from students. July 2008 Page 11 of 22

12 Single circuit: Battery holder cell cell On = 1 On/off switch Labeled 0 and 1 Off = 0 Flashlight bulb In the single circuit above, when the switch is in the 0 or off position, the bulb does not glow= 0 bulbs. When the switch is in the 1 or on position, the bulb glows= 1 bulb. July 2008 Page 12 of 22

13 Double Circuit (computer) : Battery holder cell cell On = 1 On/off switch Labeled 0 and 1 Off = 0 Flashlight bulb On = 1 On/off switch Labeled 0 and 1 Off = 0 Flashlight bulb July 2008 Page 13 of 22

14 In the computer above, the switches are the input devices and the bulbs are the output devices. The student enters binary data (0 or 1) via the switches. When both switches are in the 0 or off positions, there are 0 bulbs lit. When either switch is in the 1 or on position and the other is in the 0 or off position, 1 bulb is lit. When both switches are in the 1 or on positions, 2 bulbs are lit. Students can add more circuits and even devise ways of altering the input data. Advanced students could potentially research binary language and build eight circuits to input eight digit binary code. PART TWO- communicator Students can either obtain or build a momentary switch. A momentary switch is a switch that must be held in the on position and goes back to off when released. There are several inexpensive types of momentary switches that can be purchased, such as a cheap doorbell button switch. The other option is to have the students build their own. To build a momentary switch, each student or group will use two ice cream sticks (craft sticks), bare copper wire, a toothpick, and a rubber band. They should assemble the switch as shown below. Wrap bare copper around two ice cream sticks as shown here: July 2008 Page 14 of 22

15 Position the two sticks as shown here with extra wire trailing to the ends Place a toothpick or other round object between the sticks and put a rubber band tightly around both sticks on the opposite side of the toothpick as shown below. The wire wrapped around the other ends of the sticks should only touch when the student presses on the switch and holds the two sticks together. When released, the rubber band pulls the opposite ends together breaking the connection of the wires. Press here to make switch connect circuit toothpick Rubber band July 2008 Page 15 of 22

16 Using the momentary switch, students should assemble a circuit as shown below, using 2 flashlight batteries, a battery holder, wire and clips, and flashlight bulbs and holders. Battery holder cell cell Flashlight bulb Momentary switch By pressing and letting go of the switch, students cause the bulb to on and off. Holding the switch longer allows the bulb to stay on longer. Students can design their own coding system using alternating on and off flashes and by alternating the amount of time the bulb stays lit. Students may also begin by using actual Morse code as used in telegraphs in the 1800 s. Once the students are familiar with coding, they may devise interesting code systems of their own. This system can be altered by substituting a bell or electromagnet doorbell in place of the flashlight bulb and holder. Then it becomes an auditory communication device using alternating ringing and not ringing of the bell. Given enough wire, the student can also build blinds so that one person cannot see the other, or move to another part of the classroom and communicate using their devices. July 2008 Page 16 of 22

17 Materials Needed: PART ONE- Simple Computer Per student or group: 2 Flashlight bulbs 2 bulb holders 2 flashlight batteries 1 Battery holder 2 switches- preferably toggle or household switches with a clearly defined on/off setting 8-10 strands of insulated wire 6 inches in length, preferably with alligator clip connectors on each end. (More of all the above if students are allowed to go further with this task) PART TWO- communicator Safety Precautions: For the switch: 2 ice cream sticks 1 toothpick 1 rubber band 2 pieces of bare copper wire about 8 inched each For the rest of the circuit: 2 flashlight batteries 1 battery holder 1 flashlight bulb and holder 6 strands of insulated wire 6 inches in length, preferably with alligator clip connectors on each end. 1 DC electric bell There is almost no danger from electricity in this task. Be sure the flashlight batteries are new and in good condition. Old batteries can leak acid and corrode metal and burn skin. There is a potential for broken glass if the flashlight bulbs are dropped or crushed. July 2008 Page 17 of 22

18 Task with Student Directions: PART ONE- Simple Computer Obtain the following materials 2 Flashlight bulbs 2 bulb holders 2 flashlight batteries 1 Battery holder 2 switches 8 strands of wire Begin by building a simple circuit as shown in the diagram below. (Be sure to label the switch with a 0 in the off position and a 1 in the on position) Battery holder cell cell On = 1 On/off switch Labeled 0 and 1 Off = 0 Flashlight bulb July 2008 Page 18 of 22

19 What happens when the switch is turned to the 0 position? What happens when the switch is turned to the 1 position? Think of ways to put this circuit to use and plan a way to add to it to complete math problems using this simple computer. Design a plan for your computer on paper before you begin to build it by adding to the above design. (Your computer should use at least two circuits) In addition to your paper design, also create a data table that shows all switches and what your predictions are for each combination of switch settings and what the actual results are after you build it. PART TWO - communicator Obtain the following materials: For the switch: 2 ice cream sticks 1 toothpick 1 rubber band 2 pieces of bare copper wire about 8 inched each For the rest of the circuit: 2 flashlight batteries 1 battery holder 1 flashlight bulb and holder 6 strands of insulated wire 6 inches in length, preferably with alligator clip connectors on each end. 1 DC electric bell Electromagnetic doorbell July 2008 Page 19 of 22

20 Build a momentary switch. If a switch is purchased, skip these steps. Wrap bare copper around two ice cream sticks as shown here: Position the two sticks as shown here with extra wire trailing to the ends Place a toothpick or other round object between the sticks and put a rubber band tightly around both sticks on the opposite side of the toothpick as shown below. The wire wrapped around the other ends of the sticks should only touch when the student presses on the switch and holds the two sticks together. When released, the rubber band pulls the opposite ends together breaking the connection of the wires. July 2008 Page 20 of 22

21 Press here to make switch connect circuit toothpick Rubber band Using the momentary switch, students should assemble a circuit as shown below, using 2 flashlight batteries, a battery holder, wire and clips, and flashlight bulbs and holders. Battery holder cell cell Flashlight bulb Momentary switch July 2008 Page 21 of 22

22 By pressing and letting go of the switch, students cause the bulb to on and off. Holding the switch longer allows the bulb to stay on longer. Using Morse Code, send messages to your lab partner and have them translate what you are sending. Develop your own coding system on paper, and practice using the system to send messages to your partner. Resources: Substitute the DC bell or electromagnetic doorbell for the flashlight bulb and holder and the use the communicator to send and receive messages Homework / Extension: Have students research binary code and other code languages. Have students research computers and how they function. Have students research message coding. July 2008 Page 22 of 22