Focus: Scholastic Canada Ltd., 2010

Transcription

1 T E A C H E R S N O T E S Focus: Students explore pulleys, gears, and other machines: how they work, why people use them, how they apply and affect force, movement, and speed. Students will also learn how machines use different energy sources and impact the environment. Learning Goals: Students will have opportunities to learn how to correctly use the terms force, pulley, gear, load, block and tackle, driver that a force is a push or pull that pulleys help people move or lift loads by changing the direction of a force that two pulleys (block and tackle) decrease the force required to move a load but increase the distance over which the load must be pulled that gears can be used to change speed or increase or decrease a force that machines, such as pulleys and gears, make our lives easier how people design machines that machines use energy and that energy use impacts the environment Discussion Prompts: What is a force? What is a pulley? How does a pulley help to move or lift a load? What is a block and tackle and how does it help you to move a load? What are gears and how can they help you do tasks? How do machines, such as pulleys and gears, make your life easier? What energy sources do we use to power machines? What impact does using energy for machines have on the environment? Assessment Prompts: Do students demonstrate, in their discussions and answers to questions, understanding of the science vocabulary used in the cards for this unit? Are students able to carry out the skills of scientific inquiry, following activity procedure steps safely and accurately, making observations when appropriate? Assess students responses during discussions. - Do students understand that a force is a push or a pull and that forces can be balanced or unbalanced? - Can students explain what a pulley is and how it helps move and lift loads? - Do students understand how two pulleys decrease the force required to move the load but increase the distance required to pull the load? - Can students provide examples of machines that use gears and how the gears decrease or increase a force? - Do students recognize how machines make life easier and can they provide examples of this? - Do students understand that all machines need a source of energy, and that energy use has impacts on the environment? Are students able to follow procedures to 1) build a functioning block and tackle and 2) build and test different-sized gears? Are students able to identify examples of simple machines in activities? Links to PCSP Student Book Lighten Your Load: Card 1: see Lessons 2 and 4 Card 2: s ee Lessons 2 4 Card 3: see Lessons 5 9, and 10 Card 4: see Lessons 3-10, and 12 Card 5: see Lesson 11

2 Focus: Students explore forces and how simple machines use them. Introduce students to the topic with the video that shows machines lifting and moving loads. Discuss the video and any comments or questions students may have. Activity Description: This drag-and-drop activity shows students a tug-of-war scenario to help them grasp the idea of balanced and unbalanced forces. Learning Goals: Students explore the idea of balanced and unbalanced forces. Ask Students: In a tug-of-war, what happens if the forces are balanced? What happens if the forces are unbalanced? Assessment: Can students explain what is happening to forces when people move in a tug-of-war and when they don t move? Activity Description: This is a timed drag-and-drop activity in which students drag objects into the gravity or non-gravity columns. Learning Goal: Students identify objects that do and do not rely on gravity for their function. Ask Students: Choose one object that relies on gravity: Can you explain how you know this object relies on gravity? Can you make a list of three objects in your home that rely on gravity to work? Can you explain how each object needs gravity to work? Assessment: Can students find three examples at home of objects that rely on gravity to function? Can students provide adequate explanations for which objects they say rely on gravity and which objects they say do not? Activity Description: This is a timed activity, in which students are provided a description of the structure and function of the simple machines. The name of each simple machine is a scrambled word. Students drag and drop letters into blank spaces to descramble the word and identify the simple machine. Learning Goal: Students read about the structure and function of six simple machines and then identify the names of each. Ask Students: Choose one simple machine: Can you give an example of this simple machine and describe how it works? Assessment: Can students identify the names of the simple machines in the activity? Can students provide an example and describe the function of one or more of the simple machines? 2

3 Activity Description: Students construct a cardboard u-shaped ramp in which they allow one marble to roll and make contact with other marbles, ultimately to see the transfer of force among the marbles. After students have completed the activity, they click on the orange icon near the Think question. Students are taken to an animation of marbles transferring energy in a u-shaped ramp, much like what students built in their activity. Learning Goals: Students identify the force of gravity acting on the marbles and the transfer of energy among the marbles. Students reinforce their skills of carrying out a procedure safely, as directed, including accurately making and recording observations. Ask Students: What force acts on the marble when you let it go at the top of your ramp? (gravity) What happens to the energy in the marble when it strikes the rest of the marbles? (the energy is passed through each marble) Assessment: Do students recognize the force that acts on the marble when they let it go on the ramp? Can students describe the idea that energy is transferred among the marbles when they make contact? Did students carry out the procedure safely and accurately, carefully making and recording their observations? 3

4 Focus: Students explore pulleys and how they move loads. Activity Description: A visual and text explain to students that cranes, outfitted with a pulley system, are used to lift materials to the tops of tall buildings. Students then click on three possible crane attachments, which would be used to move specific materials. Students then click on an additional orange icon, which takes them to an animated screen that describes how tower cranes are built. Introduce students to the topic with the video of a crane working at a construction site. Discuss the video and any comments or questions students may have. Activity Description: Text describes to students the importance of the invention of the wheel. Students play a drag-and-drop activity, in which they place historical facts about wheels into their correct place in a timeline. Learning Goal: Students explore the importance of the wheel to human society and some related historical facts. Ask Students: Why was the wheel important in the past? (for moving loads) In what ways did different types of wheels help people? (to move different kinds of loads for different forms of transportation) How do you use wheels in your everyday life? Assessment: Can students provide an explanation as to why the wheel has been important throughout human history? Ask students to create a list of some ways in which they use wheels everyday in their lives. Alternatively, students can draw pictures and label them appropriately. Activity Description: Students are asked to look at images of four scenarios in which pulleys are used to do a task. They are asked to identify and write down (electronically, within the activity) how pulleys are used in each situation. Students are also asked to write down how they would do each task without a pulley. Learning Goals: Students identify and describe how pulleys are used to do the tasks shown in four situations. Students will correctly use the terms pulley, load, and force in their written answers. They also describe how they might do each task shown in the photos without pulleys. Ask Students: Look at each picture in the activity: What task needs to be done in each picture and how do pulleys help? How would you do this task without pulleys? Would the task be easier or harder to do without pulleys? How do you 4

5 continued from page 4 Learning Goals: Students explore the basic components of a building crane, which enable it to lift materials to the top of a building. Students also learn how the crane itself is built Ask Students: What kinds of materials does a crane lift and move? (e.g., steel beams) What type of system does a crane use to lift these materials? (block and tackle) How is a crane built? (The crane is built section by section as the building is constructed.) Assessment: Ask students to write one paragraph with a diagram that explains 1) the kinds of materials moved by a crane and the type of system it uses to do this; 2) how a crane is built. continued from page 4 use pulleys to make tasks easier in your life? Can you suggest an example? Assessment: Are students able to identify and describe how pulleys are being used in each picture? Did students recognize that pulleys make each task easier to do? Can students suggest other examples of how pulleys make tasks easier in their own lives? Activity Description: Students use empty thread spools, a hook, and some string to make a block and tackle (i.e., more than one pulley used together). Students then click on the orange icon near the Think question. They are taken to a screen that explains how two pulleys reduce the force you exert, but that you have to pull the load farther: You pull with half the force, but for twice as long. Students then drag and drop marbles into a pail to watch an animation of a block and tackle lifting the load. Learning Goals: Students review the idea that pulleys reduce the force used to move a load, but increase the distance you have to pull to move the load. Students reinforce their skills of carrying out a procedure safely and accurately, as directed. Ask Students: How does a block and tackle help you to move a load? (it reduces the force you have to exert to move a load ) When you use a block and tackle, do you have to pull the load a shorter or longer distance? (longer ) Assessment: Can students explain that the block and tackle system reduces the force required to move a load but increases the distance required to pull it? Did students carry out the procedure safely and accurately? 5

6 Focus: Students explore gears and how they are used in machines. Introduce students to the topic with the video that shows different-sized gears working together. Discuss the video and any comments or questions students may have. Activity Description: Text and two animation screens describe to students how low gears and high gears on a bike help the bike rider adjust the speed and force required to pedal in different conditions such as riding uphill or downhill. Learning Goals: Students explore how bicycle gears help a bike rider to adjust the speed and force of pedalling in different circumstances. Ask Students: Is it easier or harder to pedal when your bike is in low gear? Why? (easier; you don t have to apply too much force because the gears don t resist your effort very much, but you have to pedal faster) In what kinds of situation could this help you when you re riding a bike? Why? (riding uphill; you have to Activity Description: Text and animation introduce students to the idea that most tools or machines with spinning parts contain gears. Students then click on the orange icon and are taken to an activity in which they are shown a device. They must select which type of gear they think is part of the device. When students click on the correct answer, they are shown an animation and description of that type of gear and how that type of gear affects force and/or movement and/or speed. Learning Goal: Students review four of the different types of gears worm, bevel, spur, and rack and pinion. Ask Students: What is the name of one type of gear? What is one example of a device that would use that type of gear? How does the gear affect force, movement, or speed? (Encourage students to use the Activity Description: An animation shows the internal gear system of a grandfather clock. Text describes how gears of different sizes can move at different speeds, which allows the hands of a clock to move at different speeds. Learning Goal: Students explore the idea that differentsized gears make the function of clocks possible by moving the minute hand and hour hand at different speeds. Ask Students: If two gears are different sizes, how does that affect the speed of movement? (the two gears can be used to speed up or slow down, depending on what is required for the situation) Assessment: Can students explain how two gears of different sizes affect the speed movement of the gears? 6

7 continued from page 6 Internet to find other examples of devices that use the gear they describe.) Assessment: Do students understand how bevel, spur, worm, and rack and pinion gears function and how they affect force and movement? Can they provide examples of devices that use these gears? Activity Description: Students make and attach together two gears one small, one large. They turn the small gear and count how many turns it makes to turn the large gear once. Students repeat this test, turning the large gear. Learning Goals: Students will expand their understanding of how two different-sized gears affect speed and force, depending on which is the driver gear. Students reinforce their skills of carrying out a procedure safely and accurately, as directed. Ask Students: When the small gear was the driver, what did you observe? (big gear turns more slowly) When the large gear was the driver, what did you observe? (small gear turns more quickly) Assessment: Are students able to construct and connect their two gears safely and according to the procedure instructions? Are they able to explain their observations when they use the large gear as the driver and then the small gear as the driver? continued from page 6 pedal fast, but the pedalling is much easier, which helps you apply the force necessary to get the bike up the hill ) Is it easier or harder to pedal when your bike is in high gear? Why? (harder; you have to apply more force to the gears, which makes them harder to turn, but you move a greater distance in high gear) In what kind of situation could this help you when you re riding a bike? Why? (riding downhill; you pedal slower, but you travel a greater distance, plus the force of gravity on the bike takes you further) Assessment: Can students explain to you the difference between high and low bicycle gears? 7

8 Focus: Students explore how machines improve our lives and how they are designed. Activity Description: Text and a visual describe how ski lifts, using pulley systems, take the hard work out of getting up a snowy mountain to ski down. Learning Goal: Students explore how machines improve our lives. Ask Students: Have you ever gone skiing? Can you imagine climbing up a hill with your skis and poles, wearing all your winter clothes? What kind of simple machine does a ski lift use? Can you think of another device that uses pulleys to improve our lives? Introduce students to the topic with the video of a ski lift. Discuss the video and any comments or questions students may have. Activity Description: Text and a visual describe how friction can cause moving parts of machines to wear and slow down. Students click on another orange icon, which takes them to a timed drag-and-drop activity. Students drag and drop pictures of objects that either grip or slip into the correct category. Learning Goal: Students explore friction as a force and specifically as a force that affects the function of moving parts in machines. Ask Students: Why does it help to oil parts of machines? (to reduce friction) Why would you want to reduce friction in a machine? (to keep the parts working smoothly without slowing down or wearing out as quickly) Activity Description: Text and visuals introduce students to four sketches of designs for devices by Leonardo da Vinci. Learning Goal: Students explore the imagination that scientists and designers put into designing machines. And, in the case of da Vinci, students can see imagined machines that would not be built for hundreds of years after the designs were originally sketched. 8

9 continued from page 8 Assessment: Do students recognize that friction can wear and slow down the moving parts of a machine? Are they able to identify objects that grip and slip in the drag-and-drop activity? Activity Description: Students identify the different types of simple machines that are found in an illustration of a park. Students click on an orange icon to play a drag-and-drop activity. They drag and drop labels of simple machines onto the simple machines they identify in the illustration. Learning Goal: Students review their knowledge of simple machines by identifying examples and writing about how they are used. Ask Students: Which simple machines have you used before that are like the ones shown in the fun park? Are there any other amusement park rides you ve been on or any other toys you ve used that are not shown in the illustration? What are they and which simple machines do you think they use? Assessment: Are students able to accurately identify most or all of the examples of simple machines shown in the illustration? Do students write down explanations for how the simple machines are used in each example they identify? continued from page 8 Assessment: Do students recognize how ski lifts, and pulley systems in general, help improve our lives? Ask students to make a list of five devices that improve their lives and to describe how each device makes the task or job easier to do. Alternatively, students can draw pictures with appropriate labels of the devices that improve their lives. continued from page 8 Ask Students: Why do you think it is important to sketch designs for machines before you build them? Do any of Leonard da Vinci s sketches look like machines that exist today? Which ones? Assessment: Do students recognize the importance of creating sketches of designs? Do students recognize that designing and building machines takes imagination and careful thought? Ask students to write one paragraph that describes one schoolyard game or one class project they did which took imagination and thought to create. 9

10 Focus: Students explore energy sources used by machines and the impact this has on the environment. Activity Description: Text describes how chopping wood uses muscle power and a chainsaw uses energy from fossil fuels. Students click on the orange icon near the illustration of the shed and play a drag-and-drop activity to identify tools that use muscle power and tools that use energy from fossil fuels. Students click on the orange icon near the Think question, How are fossil fuels formed...?. Visuals and text describe to students how fossil fuels were formed and how people drill for it under water from oil platforms. Learning Goals: Students explore the idea that some tasks and tools use human muscle power, while other tasks and tools are powered by fossil fuels. Students explore fossil fuel: what it is, how it was formed, and how it is extracted from underwater sources. Ask Students: Make a chart that contains answers to these three questions: What tasks do you do at home that use muscle power? What machines do you use at home that use electricity or burn gasoline for their source of energy? Are there tasks that use both your muscle power and a machine? Can you describe to a partner how oil was formed and how we drill for it under water? Assessment: Are students able to accurately identify tools and tasks that require muscle power and those which require fossil fuels, or combinations of the two? Can students clearly explain how oil was formed and how we drill for it under water? Introduce students to the topic with the video that shows people using escalators. Discuss the video and any comments or questions students may have. Activity Description: A drag-and-drop activity asks students to identify the pros and cons of using stairs. Learning Goals: Students explore competing reasons for using stairs and for using powered people-movers such as escalators and elevators. Ask Students: What are some reasons for using stairs rather than an elevator? (good exercise, lower impact on environment) What are some reasons to use elevators and escalators rather than stairs? (good for people who are physically disabled, elderly, or to move heavy objects upstairs, or to travel up several storeys in a building) Assessment: Are students able to identify some different reasons for using stairs or for using escalators and elevators? Video: Robots weld car parts in a factory. 10

11 Activity Description: Text describes how energy cannot be destroyed, only converted or transformed into other forms of energy. Students are asked to make a list of machines that people use to move or go places. Students click on the orange icon at the right of the screen and play a drag-and-drop activity in which they create energy flowcharts all of which begin with the sun as the first source of energy. Students click on the orange icon near the Think question. They are taken to a screen that describes how bicycles are the most efficient peoplemoving machines. Students then play a drag-and-drop activity in which they learn about bicycles from different time periods while placing the vehicles in correct chronological sequence. Learning Goals: Students explore energy chains and how muscle and machine power all derive their energy first from the sun. Students expand their understanding of bicycles their efficient use of energy and their place in history. Ask Students: When you eat an apple, does your body destroy the food energy or does your body convert the food energy into a different form of energy? (convert ) Can you draw your own energy flowcharts, using different examples than shown in the drag-and-drop activity? Why are bicycles such a good form of transportation compared to driving a car or even walking? (Bicycles are very efficient at converting most of the energy inputs into movement energy the main purpose of the bike.) Assessment: Do students recognize that energy cannot be destroyed, only converted (or transformed) into other forms of energy? Can students create energy flowcharts, accurately identifying examples, which always begin with the sun as the main energy source? Do students understand what is meant by a bicycle being a very efficient machine? (able to convert most energy put into it into movement energy ) 11