Atom Watch the LIMBS International video. Electron Discuss how important the ability to walk is

Transcription

1 Grade Level: 4 Overview: LIMBS International is a nonprofit organization which provides prosthetics to amputees in underdeveloped countries. To achieve this goal the organization partners with existing clinics around the world. In this activity, students will gather data about prosthetic materials and their conductivity properties. In this lesson students will: Vocabulary LIMBS Conductor Insulator Electric Circuit Electromagnetic Field Atom Watch the LIMBS International video Electron Discuss how important the ability to walk is Closed Circuit Use a chart to track conductivity properties Open Circuit Observe how insulators and conductors respond in a circuit Current Compare and contrast insulators and conductors properties Electricity Bonus Word: Students learn: Prosthetic Not everyone has the ability to walk, but LIMBS is helping them walk again Charts can be used to categorize and group materials during experiments Conductors all have similar properties Insulators all similar properties Conductors allow energy to pass, while insulators prevent energy from passing. Electricity travels in a closed path called a complete circuit Electromagnetic fields can be created by passing electricity through a wire and can be turned on and off Students will be able to: Understand that not everyone is the same and to empathize with others. Differentiate between conductors and insulators. Demonstrate that electricity travels in a closed path. Create an electrical circuit. Explore an electromagnetic field.

2 STEM Content Tie-In: Students will collect data, analyze properties and draw valid conclusions by utilizing the scientific method Levels of Thinking: Analysis and Modification seeing patterns organization of materials by their properties identification of components to the prosthetic through observation PRACTICE: The following question allows students to apply scientific knowledge that various materials conduct electricity and can reason which material would best conduct energy. Which of these is the best conductor of electricity? F Glass rod G Cotton string H Plastic tubing J Copper penny

3 Materials: Chart paper Markers Paper bags Items for paper bags Student Science Journals Day 1 Introduction: Show and discuss the LIMBS video ( Read the foundation knowledge for the students to get the overview of electricity, conductors and insulators. (See attached at end of lesson) Now ask: What does LIMBS international do? Why it is important to be able to walk? Discuss the emotional impact of losing a limb and how that impacts their daily lives. Transition into how easy it is to walk into the kitchen and open a refrigerator door and grab something to eat. Explain that like a refrigerator has moving parts so do our limbs. Then open the discussion into what types of materials would be good to build and create a new limb. What type of material can be used as a conductor? What type of material can be used as an insulator? What is a circuit? How can we create an electromagnetic field?

4 Student Activity: Hands on activity: In this activity, students will determine the temperature of water in different cups to investigate the role of conductors and insulators and how the material that prosthetics are made of need to remain constant, not able to melt easily, and be useful long term. Preparation Gather a variety of cups for each group to test their ability to conduct or insulate heat. You may wish to have each group conduct the tests with different materials if you have more than three or four types of cups available. Alternatively, each group can be in charge of one cup and measure the changes accordingly. Exercise caution with hot liquids and be sure students are aware of how to handle the cups carefully. You may wish to make a table on the board as an example for students to record their results, listing 5, 10, and 15 minute intervals, cup materials, and then gives room for students to enter each temperature. Background for Teacher Conductors and insulators work in different ways. Conductors permit the flow of heat or electrical energy, such as with metal wires, glass, or paper cups. Insulators on the other hand prevent the flow of heat or electrical energy, such as with double paned windows, travel mugs, or Styrofoam. Substances that insulate well will show a smaller change in temperature here than those that conduct energy well. Procedure Ask students why we might want to keep hot things hot or cold things cold. Allow time to respond. Introduce the cups to students, and explain that they will be determining which are the best materials for keeping our hot water hot the longest. After adding hot water to each, have students record the initial temperature. Then have students record the temperature after 5, 10, and 15 minutes. Reflect on the temperature changes in each cup. Those with larger changes let heat pass, so are better conductors. Those with the lowest temperature change are insulators. Have student groups move to alternative groups to answer each question. Groups will either list the answers or build the graph, and then all students return to their original group to share their results. Explain to the children that materials that are making up these prosthetic limbs must be durable and yet affordable since they are being used in remote undeveloped countries that have limited funds and resources. In order to achieve this balance LIMBS uses a plastic called Delrin to make the LIMBS knee.

5 Ask: What are the benefits of using Delrin? Possible answers: It is waterproof Lightweight Does not conduct heat Is affordable and available around the world Class follow-up activity: Reflect in their notebooks how having a properly made limb changes lives. How would they feel if they had received a prosthetic limb?

6 Materials: C-leg video ( Small light bulb (or a flashlight bulb) Paper clips Electrical tape (Scotch tape also works) 2 batteries (with the correct voltage for your light bulb) Bulb holder (optional) 2 alligator clip wires or aluminum foil Battery holders (optional) Day 2 Introduction: Student will identify the different between expensive, high-end prosthetic and the products that LIMBS provides. Watch the video describing how one of the best knees in the world (the C-leg) function: watch?v=tua9wmshqdk The C-leg can cost up to $100,000 A LIMBS leg costs $300 Discussion: Ask: How is the C-leg different than the LIMBS leg? It has microprocessors that are constantly adjusting the leg s movement during walking It is more expensive It needs a lot more maintenance it something goes wrong It is not waterproof The goal of LIMBS is to bridge the gap between quality and affordability. The LIMBS knee functions just as well as a $2,000 knee that you can buy in the U.S.

7 Student activity: Build a simple circuit A circuit is a path that electricity flows along. It starts at a power source, like a battery, and flows through a wire to a light bulb or other object and back to other side of the power source. You can build your own circuit and see how it works with this project! Part 1 - Making a Circuit: 1. Connect one end of each wire to the screws on the base of the light bulb holder. (If you're using foil, ask an adult to help you unscrew each screw enough to fit a foil strip under it.) 2. Connect the free end of one wire to the negative ("-") end of one battery. Does anything happen? 3. Attach the free end of the other wire to the positive ("+") end of the battery. Now what happens? Part 2 - Adding Power 1. Disconnect the battery from your circuit. Stand one battery so that the "+" end is pointing up, then set the other battery next to it so that the flat "-" end is pointing up. Tape around the middle of the batteries to hold them together. 2. Set a paperclip across the batteries so that it connects the "+" end of one to the "-" end of the other. Tape the paperclip in place with a narrow piece of tape (do not tape over the metal battery ends). 3. Turn the batteries over and tape one end of a paper clip onto each of the batteries. Now you can connect one wire to each paper clip. (The bottom of the battery pack should only have one paper clip do not connect a wire to it.) 4. Connect the free ends of the wires to the light bulb. Discuss the similarities between the simple circuits, how our body s nervous system helps us walk and how the C-leg functions. Homework follow-up questions Why are electric cords, such as on a toaster or a lamp, covered with a rubber coating? How does electricity move through wires? When we turn electrical devices on and off, we are using open and closed circuits. What happens when you turn off the television? How would you create and electromagnetic field? What type of tools, appliances or devices might require an electromagnetic field for its use?

8 Materials: Circuit with light bulb & 2 batteries Extra alligator clip wire (or aluminum foil wire) Objects to test (made of metal, glass, paper, wood, and plastic) Day 3 Introduction: In a conductor, electric current can flow freely, in an insulator it cannot. Metals such as copper typify conductors, while most nonmetallic solids are said to be good insulators, having extremely high resistance to the flow of charge through them. "Conductor" implies that the outer electrons of the atoms are loosely bound and free to move through the material. Most atoms hold on to their electrons tightly and are insulators. In copper, the valence electrons are essentially free and strongly repel each other. Any external influence which moves one of them will cause a repulsion of other electrons which propagates, "domino fashion" through the conductor. Simply stated, most metals are good electrical conductors, most nonmetals are not. Metals are also generally good heat conductors while nonmetals are not. Student Activity: Insulator or Conductor? Materials that electricity can flow through are called conductors. Materials that stop electricity from flowing are called insulators. You can find out which things around your house are conductors and which are insulators using the circuit you made in the last project to test them! What To Do: 1. Disconnect one of the wires from the battery pack. Connect one end of the new wire to the battery. You should have two wires with free ends (between the light bulb and the battery pack). 2. You have made an open circuit and the bulb should not light up. Next, you will test objects to see if they are conductors or insulators. If the object is a conductor, the light bulb will light up. It is an insulator, it will not light. For each object, guess whether you think each object will complete the circuit and light up the light bulb or not. 3. Connect the ends of the free wires to an object and see what happens. Some objects you could test are a paper clip, a pair of scissors (try the blades and the handles separately), a glass, a plastic dish, a wooden block, your favorite toy, or anything else you can think of.

9 What's Happening? Before you test each object, guess whether it will make the light bulb light up or not. If it does, the object you're touching the wires to is a conductor. The light bulb lights up because the conductor completes, or closes, the circuit and electricity can flow from the battery to the light bulb and back to the battery! If it doesn't light up, the object is an insulator and it stops the flow of electricity, just like an open circuit does. When you set up the circuit in step 1, it was an open circuit. Electrons could not flow all the way around because two of the wires were not touching. The electrons were interrupted. When you placed an object made of metal between the two wires, the metal closed or completed the circuit the electrons could flow across the metal object to get from one wire to the next! Objects that completed the circuit made the light bulb light up. Those objects are conductors. They conduct electricity. Most other materials, like plastic, wood, and glass are insulators. An insulator in an open circuit does not complete the circuit, because electrons cannot flow through it! The light bulb did not light up when you put an insulator in between the wires. If you're using wires or alligator clips, take a good look at them. Inside they are made of metal, but they have plastic around the outside. Metal is a good conductor. Plastic is a good insulator. The plastic wrapped around the wire helps keep electrons flowing along the metal wire by blocking them from transferring to other object outside of the wires. Have students chart the conductivities to formulate a chart to see insulators and conductors throughout experiment. Homework follow-up: Go home and find and list 20 insulators and twenty conductors. Bring in one item from your list to test to see if you made a logical guess.

10 Materials: Three pieces of insulated electrical wire Long coil of uninsulated copper wire Two size D batteries Metal paper clips Tall drinking glass Resistor Metal spoon or screwdriver Compass Day 4 Introduction: Discuss magnetic fields and provide the students with the definition. Magnetic fields are the portion of space near a magnetic body or a current-carrying body in which the magnetic forces due to the body or current can be detected. Student Activity: Instructions Power Source Tape the two batteries together so that each has a different end facing up. Make sure they are very secure and do not roll, or else you may lose your electrical current. Take two of the insulated wires and attach one to each of the paper clips. One should be attached on the end to each battery. Place one of the paper clips across the tops of the two batteries. If the paper clip does not reach to the center of each battery, you may have to unbend it so that it is longer. Affix a strip of tape along the paperclip and halfway down each battery. Be sure to keep the paper clip in contact with the center of each battery and keep the free end of each wire accessible. Turn the batteries over, and do the same to the other side. Again, make sure that this paperclip also makes contact with the center of the ends of the batteries both before and after affixing the tape. Electromagnet Leave about six inches of copper wire straight, and then start wrapping the rest of your copper wire around the middle of the glass, staying away from the mouth and bottom as you wind. After at least 20 coils around the glass, make sure you have at least six inches of copper wire straight and free at this end of the coil as well. Connect one of the wires from the power source to one of the free ends of your copper wire coil. Make sure the copper connects with the metal part of the insulated wire. Connect the other wire from the power source to your resistor. The third copper wire will go from the other terminal of the resistor to the other free wire of the copper coil. Test the magnetic field inside the glass by taking metal objects and placing them inside the glass. They should become magnetized while the current is flowing through the copper coil. Paperclips will stick together. The metal part of a screwdriver or the spoon sticking out of the glass should be magnetized while the current is on, attracting other metal objects to it.

11 Electromagnetic Field Try to keep your compass still and level on the table. Watch the compass needle as you close and reopen the circuit. Draw what happens in your journal. Homework follow-up Have students go home and discuss how a magnetic field could impact a person s prosthetic limb. Would it impact them? Foundation Knowledge Energy is power, the ability to do work. Every time anything moves, whether it s the wind, water, cars, trees, people, clocks, or animals, it is energy that makes it happen. All movement is energy. It takes energy to cook a meal, ride a bicycle, speak to a friend, turn on a computer, or listen to a song. We use energy every day. And just like a car cannot run with an empty fuel tank, we need fuel to have the energy to do out tasks. We gain our energy by consuming food. However, energy comes in different forms, all of which provide the power for an object to do work. Mechanical energy is the energy which is possessed by an object due to its motion or due to its position. Mechanical energy can be in the form of kinetic or potential energy. Kinetic energy is the energy which comes from movement, and potential energy is the stored energy which comes from an object s placement. A ball flying through the air has mechanical kinetic energy due to its mass and the speed of its movement. A tightly-wound spring in a windup toy has potential (stored) energy which will change to kinetic energy (movement) when the spring is released. The string of a bow when drawn back to shoot an arrow has mechanical (potential) energy, and, when released, changes to kinetic energy to rapidly push the arrow away from the bow. A fire, a hot cup of coffee, or a heating stove has thermal or heat energy. Temperature is really a measure of how much thermal energy an object has. The higher the temperature the faster the particles, or molecules, of an object are moving. A cooking stove heats the air inside the oven and when the cake mixture is placed in the oven, the thermal heat of the air is transferred to the cake and it bakes. A microwave works differently; it uses microwaves (longer waves around a food in length are the ones that help heat food in the microwave itself) to make the particles inside the food move more rapidly. The resulting heat from the faster moving particles cooks the food. Light energy is something we take for granted, but it is becoming even more important than ever. Light is able to travel through space, unlike sound, that needs air or some other medium to be transmitted.

12 The portion of the electromagnetic spectrum that humans can see is commonly called light. Light energy travels in a straight line, but it can be reflected. Light is reflected when it bounces off a shiny surface, such as a mirror. Light can also be refracted, meaning it can be bent when it travels from one medium to another. Because light travels slower in water than in air, a pencil placed in a cup of water will appear broken at the point of entry into the water. Curved lenses in telescopes refract light in order to magnify the picture. Advances have been made even recently to utilize light energy beyond just illumination. Laser lights have become important tools for doctors in surgery, for the manufacture of CD and DVD players and computers, and even for teachers and speakers who use laser pointers in their presentations. All matter is made up of atoms. Electrical energy is created when electrons, small particles of atoms, are caused to move along a path called a circuit. For the electrons to flow and electricity to be evident, the circuit must be closed, that is to say the path along which electrons are flowing must not be broken, or open, anywhere along the way. When we turn on a light, we are closing an electrical circuit and the lights come on. When we flip the switch off, we open the circuit, and the electricity ceases to flow. Materials through which electrons flow easily, such as copper wire, are called conductors, while materials such as rubber or plastic, which do not allow electrons to flow through them as easily are called insulators. When electricity passes through coils of wire, it can create an electromagnetic field. All electric motors in everything from toy cars to powerful fans use electromagnetic fields to create their power. When we listen to someone speak, we are doing so because of the effects of sound energy. Sound is created when an object vibrates. The vibration of the object pushes the air molecules nearby which travel as sound waves to the listener. Our ears are designed to be sensitive to these waves of sound, which our brain translates back into the voice which we hear. Sound waves can be demonstrated by striking a metal rod and feeling the vibration of the ringing rod or by simply placing our hand on our throat and speaking. Sound energy requires a medium such as air or water to transmit, which is why sound does not travel in space. Energy can be altered or changed within objects to meet the needs of people. We can change the amount of sound energy in a radio or television to adjust the volume up or down. We can adjust the amount of electrical energy in a light bulb if we want a room to be brighter or dimmer. A television is an example of how energy can be changed to meet our needs. A television is powered by electrical energy, but the TV changes the electrical energy into light energy so we ll see a picture and to sound energy so we ll hear the voices. Without sources of energy, the Earth would be a lifeless planet. We have learned how to harness the various forms of energy for our use, and in doing so, we have made our lives more comfortable and enjoyable.