Science Is A Verb! Elementary. Part 1 LET S DO IT! ISBN

Transcription

1 LET S DO IT! Science Is A Verb! Elementary Part 1 ISBN

2 Contents INTRODUCTION Lab Title How bright can you make the light bulbs? Students know how to design and build simple series and parallel circuits by using components such as wires, batteries, and bulbs. What does a compass detect? Students know how to build a simple compass and use it to detect magnetic effects, including Earth s magnetic field. How can electricity cause magnetism? Students know electric currents produce magnetic fields and know how to build a simple electromagnet. Students know the role of electromagnets in the construction of electric motors, electric generators, and simple devices, such as doorbells and earphones. How Do Charged Objects Interact? Students know electrically charged objects attract or repel each other. How Do Magnets Interact? Students know that magnets have two poles (north and south) and that like poles repel each other while unlike poles attract each other. The Electricity Challenge Students know electrical energy can be converted to heat, light, and motion. How are all living things connected in an ecosystem? Students know plants are the primary source of matter and energy entering most food chains. Students know producers and consumers (herbivores, carnivores, omnivores, and decomposers) are related in food chains and food webs and may compete with each other for resources in an ecosystem. Students know decomposers, including many fungi, insects, and microorganisms, recycle matter from dead plants and animals. Students know many plants depend on animals for pollination and seed dispersal, and animals depend on plants for food and shelter. Page

3 lab title What Are the Living and Non-Living Things in an Ecosystem? Students know ecosystems can be characterized by their living and nonliving components. Students know many plants depend on animals for pollination and seed dispersal, and animals depend on plants for food and shelter. How Do Adaptations Help Animals and Plants Survive? Students know that in any particular environment, some kinds of plants and animals survive well, some survive less well, and some cannot survive at all. Can Microorganisms be Beneficial? Students know that most microorganisms do not cause disease and that many are beneficial. What Happens During the Rock Cycle? Students know how to differentiate among igneous, sedimentary, and metamorphic rocks by referring to their properties and methods of formation (the rock cycle). How can you tell minerals apart? Students know how to identify common rock-forming minerals (including quartz, calcite, feldspar, mica, and hornblende) and ore minerals by using a table of diagnostic properties. Does Everything Happen At The Same Speed? Students know some changes in the Earth are due to slow processes, such as erosion, and some changes are due to rapid processes, such as landslides, volcanic eruptions, and earthquakes. How Can Rock Be Broken? Students know natural processes, including freezing and thawing and the growth of roots, cause rocks to break down into smaller pieces. Students know moving water erodes landforms, reshaping the land by taking it away from some places and depositing it as pebbles, sand, silt, and mud in other places (weathering, transport, and deposition). Page

4 Introduction to the lab manual: This lab manual provides structure for teachers who wish to engage students in hands-on interactive learning but also provides support for teachers who are more comfortable with inquiry based learning. If you are a teacher who is taking their first dive into hands-on Science, the background material is designed to provide enough structure to help support the organization of the lab and its materials. Most of the materials are commonly found in local supermarkets and department stores at a nominal cost. A few materials, like scales and hand microscopes can be found on-line. The lab sheets can be given to students so they follow step by step, or they can be told a general structure to follow. The critical portion of any lab is to have a thorough discussion of the results and their thinking after the experiment is completed. It is suggested that you take as much time as the experiment to have this discussion with students. The real learning occurs not from the hands-on experiment, but from a deep discussion of the experiment, while making connections to the concept they are learning. For this reason, it is suggested that the students do the experiment FIRST, and then have the students learn the concepts. They will have a better understanding of the concept if they first conduct an experiment, gain the experience, and then discuss a new concept. Even without a strong Science background, get into the habit of asking questions. The process of asking questions and being inquisitive will generate more excitement for students and will engage them in a deeper way of learning Science. I don t know is as important to learning as having all the answers. Together you can learn Science and discover the major ideas that Scientists research. If you are an experienced teacher, the Teacher Guided Questions to Inquiry are designed to provide prompts for students. These questions are not intended to be assessment questions, but ones that will engage students in the general direction of the benchmark. The teacher may select one or two, but not all of them, to have students start on an open inquiry approach to learning. The students will engage in their own experiment, create their own procedures, and make conclusions from their data. For this reason, there are no answers to those questions. They are open ended and can be used to formulate interesting experiments for advanced students. The slight variation in some of the questions in each of the labs is designed to provide a sufficient number of prompts at various levels of Blooms Taxonomy to engage students. Throughout the year, encourage questioning, student dialogue, and the scientific process. There is no one exact scientific method as is often suggested. The process of learning about the world and universe, drawing conclusions from facts, and building these facts into strong scientific theories is the work of Science. Science is always growing, stretching, and expanding its knowledge base. It is about challenging well supported ideas to discover weakness. This exactly what students should be encouraged to do! And in the end, Science is not something to study, it is something to do! Science is a VERB!

5 Elementary Science Curriculum How bright can you make the light bulbs? Description: Students are challenged to design a circuit that causes three light bulbs to be as bright as possible. The students will be able to make only two possible circuits a series and a parallel circuit. After students conduct the lab, the teacher should discuss the types of circuits they created and then give names to each type (i.e. series and parallel). Student Materials (per group): volt light bulbs 1 C or D battery (1.5 volt max) 4 pieces of wire Additional Teacher Materials: Wire cutter/stripper Candle Book of Matches Piece of steel wool Background and Misconceptions: There are two types of circuits: Series and Parallel. In a series circuit, the light bulbs are arranged one after another. This causes the voltage from a battery to reduce incrementally over each light bulb. In other words, the voltage used up by each light bulb adds up to be the total voltage of the circuit. This is also called a voltage drop, so whether you add or subtract, the total is still the same. The current in a series circuit is constant. The resistance of each light bulb adds up on each light bulb to be equal to the total resistance of the circuit. (Yes, light bulbs are actually resistors. That is what causes them to glow brightly). Figure 1 - Imagine looking down on a pipe with three bundles of debris. This is like three light bulbs in series. Each bundle of debris slows down the water. In the same way, the light bulbs reduce the current flow, and they each are lit dimly.

6 One way to think about a series circuit is to imagine a dam with water behind it. Now imagine that there are three bundles of debris, one after the other that go from the back of the dam to the front. This debris is similar to placing light bulbs in a circuit. If there is debris in the pipe, this resists the flow of water through the pipes and less current flows. A light bulb is a resistor, so adding more resistors is like adding more debris. Eventually, with enough light bulbs, the current will stop flowing, just as adding more debris will eventually stop the water from flowing. In a parallel circuit, the voltage across all three is equal to the total of the battery. So instead of the light bulbs using up small amounts of the voltage down the circuit, in a parallel circuit it is all used at once by all three. If the battery is 1.5 volts, and assuming there is nothing in the circuit other than the light bulbs, the voltage drop will be 1.5 volts across each one. No, this doesn t add to be 4.5 volts, because the voltage doesn t add across a parallel circuit, like it does across a series circuit. What does add is the current. This is why if you plug in many electronic devices into a parallel circuit (which is what is found in most homes) the current will increase to the point that it will trip the circuit breaker to protect the wires in the wall from getting too hot. The resistance of each bulb is determined by adding the inverse of each light bulb s resistance, and then taking the inverse again of the total of each inverse. The effect of this is that as the number of light bulbs in a circuit increases the overall resistance of the entire circuit decreases, which causes the increase in the current. If we use the dam analogy for parallel circuits, instead of a series of pipes, one after the other from front to back, we place pipes next to each other so that all the pipes carry water from behind the dam. Closing any one pipe doesn t affect the amount of water flowing through the other pipes. Figure 2 - Three pipes next to each other are like three bulbs in parallel. They each let current flow without affecting the others next to them. Removing one will not stop current from flowing through the other two.

7 3 It is important to note that the students should determine on their own which circuit will produce light bulbs that glow as brightly as possible. Then, have the students present drawn pictures of them on white boards or on overhead transparencies. Have all the students look for items in common in each circuit. By questioning the students, you should be able to get them to recognize that each circuit is the same. Each circuit branches off into three parallel parts (with the light bulbs next to each other). Ask them if they know of a word that describes this setup. (If they have not been introduced to this word in mathematics, they may have difficulty). This is called a PARALLEL circuit because all the light bulbs are parallel or next to each other. Repeat the same procedure for the light bulbs that did not light up as brightly. Again, have students recognize common factors and then question them on how this setup is different from a parallel circuit. Introduce the word SERIES circuit and point out that the light bulbs are in series, one after another. Figure 3- Light bulbs in a series circuit. Notice that the electricity will flow through one after another. If you remove one light bulb, they will all go out. Figure 4 - Light bulbs in a parallel circuit. Notice that the electricity enters all three light bulbs at the same time. If one light bulb is removed, the other two will continue to glow.

8 4 Preparation: A simple source of 1.5 volt light bulbs is Christmas tree lights. These lights can be cut away from the string and strip the wire from the bottom 1 cm of the wire. Prepare the wire using bell wire found at hardware stores. Unlike previous labs that have required the use of thinner bell wire, it is suggested that thicker wire is used, such as gauge wire. The wire often has a very thin layer of insulation that must be removed prior to use. The best way to do this is to use a candle to burn 1 cm of insulation from each end of the wire so that students can connect the wires to the battery and light bulb. If the ends break, simply burn off more. Use steel wool to clean the burned insulation to expose clean bare wire To place the lights in series, connect one light bulb after the other like shown in the picture. Each lead will be connected to only one bulb, and when all are put in series, there will be two points where the light bulbs are connected, and two leads that are not connected. To place the lights in parallel, twist all the leads on one side together, then the other side together. All the lights bulbs will be connected only in two points. These wires are provided only to assist the students. It is possible that the students will not use the wires to connect the light bulbs to the battery. You may want to point this out during the discussion. Teacher Guided Questions to Inquiry: Use these questions to get the students started on their own inquiry! How can you make a light bulb as bright as possible using only 1 battery? How can you make 3 light bulbs as bright as just 1, using only 1 battery? What are the different ways you can light up a set of light bulbs? How can you set up a circuit so that when one bulb is removed they all go out? How can you set up a circuit so that when one bulb is removed, no others go out? Additional Hints: Make sure students do not connect more than one battery to the light bulbs. The light bulbs may blow.

9 5 How bright can you make the light bulbs? TEACHER ANSWER KEY Description: You learned in a previous lab that a simple circuit is needed to make a light bulb glow, and this simple circuit always involves a power source (such as a battery) a resistor (we are using light bulbs) and wires. To make the circuit work the loop from the battery, to the light bulb and back has to be solid. If there is a break in the loop then electricity will not flow. In this lab, you are going to experiment to find out what way to set up a circuit to make three light bulbs glow as brightly as possible and determine the difference in the circuits you make. Materials: Christmas tree lights (3 per group) 1.5 volt battery Wires Procedures: 1. Using the three light bulbs and a 1.5 volt battery and wires, find a way to make the light bulbs all light up at the same time so they are glowing as brightly as possible. 2. As a point of comparison, find out how bright one light bulb is when connected to the battery. 3. Keep track of what you do and how you do it. Draw pictures of each arrangement and write down a sentence about how you made the light bulbs glow. Observations of light bulb intensity with only one battery and one light bulb. The bulbs glows very brightly and it is not possible to see the filament inside, other than it is the source of the light.

10 How bright can you make the light bulbs? Describe the results of trying to make the bulb glow the brightest possible. Use only 1 battery to observe the effect. Does not glow as All the light bulbs are as brightly as before: bright as before: Questions: 1. What did you need to do to make the light bulbs glow with the greatest intensity? Draw a picture of it here. All the light bulbs have to be placed next to each other, with all the lights connected together at two points only. Then these two places where they are twisted together are connected to the light bulb. 2. What type of setup did you have when the bulbs were not glowing brightly? Draw a picture of it here. All the light bulbs are connected together in a string. They are connected one after another and the loose end of the first light bulb is connected to the battery. The loose end of the last light bulb is connected to the other end of the battery.

11 How bright can you make the light bulbs? 3. Based on the results of your experiment, what type of circuit is a string of Christmas tree lights that turns off when one light bulb is pulled out? The type of circuit is a series circuit, like the ones that we had connected one after the other. 4. Based on the results of your experiment, what type of circuit is typically found in a home? This type of circuit is a parallel circuit. This is like the ones we had connected so they were all connected at only two points. 5. In one of your arrangements, the light bulbs glowed dimly. Describe what was happening to the voltage supplied by the battery. The total voltage of the battery was being used up on each one. Since the light bulbs are all the same, and the battery has 1.5 volts, then it would be expected that each light bulb used 0.5 volts. (So the voltage used from each light bulb adds up to be 1.5 volts).