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Mini-1 Subject / Course: BIOLOGY Grade Level: Grade 6 Topic: What are circuits? TC Name: Ms Sayer Date: 2011-2012 Duration of lesson: 50 minutes 1. Objectives and Skills 1. 2. 3. 4. Make models of simple circuits. Measure voltages and amperages in circuits. Explore Ohm’ s Law. Explore parallel and series circuits 2. Materials 1. Compatible Computer 2. Access to http://phet.colorado.edu/en/simulation/circuit-construction-kit-dc 3. Activities Introduction -Hello students My name is Heather and I will be your Science Instructor. I am so glad to meet all of you and I hope that we will have a lot of fun. -Lets go through a couple class rules real fast. a) If you have a question just raise your hand no talking when someone else is talking. b) If you need to go to the washroom just tell me. c) While in the lab we need to make sure we aren’t being too goofy, we need to have fun but we can’t be fooling around too much. Ok students today we are going to investigate electricity and how it works in Circuits -First off what do you know about electricity? Scientific Understanding To understand electrical current, consider the structure of an atom. Atoms consist of three types of particles: protons (red) and neutrons (green) inside the nucleus, electrons (blue) outside the nucleus. Protons are positively charged and electrons are negatively charged. Some atoms hold on to their electrons tightly. Other atoms lose their electrons easily. Within a metal, many electrons float among the atoms, free to move one way or another. Electricity is the movement of these electrons in a circuit. Why do they move? Lab Procedure 1. Have students access the site http://phet.colorado.edu/en/simulation/circuit-construction-kit-dc 2. Have the students grab a wire from the simulation. Explain that the little silver balls are electrons. In order to have electricity we need the electrons to move. Are they moving? No 3. Have students add a battery. In order to have electricity we need the electrons to move. Are they moving? No 4. Have the student use the wire to complete the circuit. A battery is a device that uses a chemical reaction to produce current. Batteries usually consist of two kinds of metals and an acid. On the negative terminal of the battery, the acid reacts with one of the metals. The reaction produces positively charged ions and electrons. When a wire is connected to the battery, electrons from the wire react with the ions on the positive terminal of the battery. This creates a net flow of electrons from the wire to the positive terminal, and a flow of electrons from the negative terminal to the wire. (Individual electrons move slowly within the wire from one terminal to the other.) What happened in our circuit? We had what is called a short circuit. When electrons move they create a lot of energy if this energy isn’t put to some use (ex lighting a light bulb) then it stays in the wire and heats it up. This can cause great damage when it occurs in the wires of a house. 5. Have the student use the wire to complete the circuit containing both a battery and a light bulb. Questions: What did you notice about the speed of the moving electrons? Why do you think this is the case? What is happening? The light bulb is acting a resistor. A resistor is a device that slows the movement of electrons. As electrons enter the light bulb they are forced through a small wire called a filament. This filament acts like a cattle shoot that forces the electrons to slow down and move single file through the wire. 6. Have the students add a battery to their circuit. Questions: What did you notice about the speed of the moving electrons and the brightness of the bulb? Why do you think this is the case? Batteries have things called voltage ratings. What is voltage it? The pressure that pushes electrons in an electrical circuit, or electromotive force, applied to electrons to make them move. And it is measured in volts (V) So a 9 volt battery will give the electrons more of a push then a 3 volt battery. 7. Have the students add a second light bulb to their circuit. 8. Have the students add a third light bulb to their circuit. Questions: What did you notice about the speed of the moving electrons and the brightness of the bulb? Why do you think this is the case? What is happening? Well the batteries have a certain votage or a finante about of push. The more resisters you place in the circuit the less push each light bulb receives. This circuit is called a series circuit because the bulbs are hooked up in one long “series” or line. Also when you break one chain on your series circuit all of your light bulbs go out (like in the old style Christmas lights) 9. Remove two of your light bulbs and make a gap in your circuit. Go to the grab bag and play with the different objects inserting them into your circuit. Find out which objects allow electricity to flow and fill in the data table: Objects that allow electricity to flow Objects that do NOT allow (conductors) electricity to flow (insulators) Questions: What do you notice about the things that allowed the electrons to flow? These are called conductors and these materials have a lot of free electrons with in their chemical make up. What do you notice about the things that did not allow the electrons to flow? These are called insulators and these materials don’t have a lot of free electrons and are thus very strong resistors. 4. Curriculum Connections 1-Investigate, with guidance, the nature of things, demonstrating an understanding of the procedures followed. 2-Recognize pattern and order in objects and events studied; and, with guidance, record procedures and observations, using pictures and words; and make predictions and generalizations, based on observations. 3-Construct, with guidance, an object that achieves a given purpose, using materials that are provided 4-Demonstrate positive attitudes for the study of science and for the application of science in responsible ways. 5-Describe the appearances and life cycles of some common animals, and identify their adaptations to different environments. 6-Identify requirements for animal care. 7-Use, safely, a variety of tools, techniques and materials in construction activities. 8-Construct structures, using a variety of materials and designs, and compare the effectiveness of the various materials and designs for their intended purposes. 9-Evaluate the suitability of different materials and designs for their use in a building task. 5. Reflections (Effectiveness of Lesson and as a Teacher)