What Are Pulleys and Gears?

Transcription

1 What Are Pulleys and Gears? Student Book 4c, pages Understanding Reading Strategies Instructional Focus MAKING INFERENCES Making inferences is the process of combining what you already know with new information and clues the writer gives you to draw conclusions. Instructional Approach SHARED READING Transparency 44: Gears Turning Gears What Are Pulleys and Gears? Student Book 4c, p. 44 Selection available on audio CD. Expectations LANGUAGE O: Oral R: Reading W: Writing ML: Media Literacy O R R W Communicate ideas and information orally in a clear, coherent manner Make inferences using stated and implied ideas from the text as evidence Extend understanding by connecting ideas in texts to their own knowledge and experience, to other texts, and to the world Write more complex texts using a variety of forms SCIENCE CONNECTION Structures and Mechanisms: Demonstrate an understanding of the characteristics of pulleys and gears. About This Selection This informational explanation describes how pulleys and gears are special kinds of wheels and provides examples of how they are used. This text will be accessible to most students. It is written in clear sentences and uses informative illustrations and photographs. ACCESSIBILITY Easy Average Challenging ASSESSMENT FOR LEARNING Ongoing Observation Students who understand will use what they already know to make inferences use information from the text to make inferences ask himself/herself questions about what the writer hasn t included to make inferences explain how making inferences helps the reader to understand the text Differentiated Instruction If students do not understand, use Inferring While Previewing (see Differentiated Instruction: Extra Support, p. 19) For extra challenge, use Making Inferences in Science (see Differentiated Instruction: Extra Challenge, p. 20) Assessment Key Assessment Questions How did you use what you already know to help you make inferences? What clues from the text helped you to make inferences? How did asking questions about what the writer did not include help you to make inferences? How did making inferences help you to understand what you read? Assessment Tools BLM 2: Oral Language Tracking Sheet BLM 3: Small-Group Observation Tracking Sheet BLM 5: Strategy Rubric Strip Making Inferences What Research Says about Reading Strategies Comprehension instruction is best when it focuses on a few well-taught, well-learned strategies (Duke & Pearson, 2002). What Are Pulleys and Gears? 17

2 Shared Reading Transparency 44 Use Transparency 44: Gears Turning Gears and its related teacher notes in Transparencies for Shared Reading and Modelling to model how readers make inferences. Before BUILDING BACKGROUND KNOWLEDGE 1. Show students a large, heavy book. Ask: How would you lift this book? (by lifting it with my hands) 2. Set out a chair and a rope. Ask students how these objects might be used to lift the book. Let students try several ways to lift the book by using these objects. 3. Demonstrate the method illustrated on Student Book page 45 to lift the book. Explain to students that this method uses a pulley. It is easier to move things with a pulley because it is often physically easier to pull down than to lift up. 4. Remind students of the strategies for making inferences modelled in Transparency 44: Gears Turning Gears. During INTRODUCING THE TEXT 1. Tell students to look at the title and illustrations on Student Book pages Ask: What do you think you are going to read about? (pulleys and gears) What clue in the title suggests that you will learn about pulleys and gears? (the words pulleys and gears appear in the title; if a title is a question, the text answers the question) Understanding reading strategies Making Inferences Making inferences helps you get more out of your reading than just the facts written on the page. When you make inferences, you draw conclusions by combining what you already know with new information and clues the writer gives you. Think about what you already know and the information the writer includes. Why are wheels called simple machines? 44 Pulleys and Gears Vocabulary Written by Angela Royston Illustrated by Dave Mazierski Pulleys and gears are special kinds of wheels. A wheel is a simple machine that lets you use a small force to produce a big result. For example, wheels are often used to make it easier to move things. Pulleys and gears are wheels that make it easier to lift heavy loads. A pulley is a wheel with a groove around the outside for a rope or cable to fit into. A pulley on this fishing boat helps fishers pull in their net. cable a strong, thick rope, usually made of wires twisted together force in science, any cause that moves, changes, or stops an object friction a rubbing of one thing against another groove a narrow channel that has been cut or dug evenly into a surface hub the central part of a wheel load in science, the mass of the object being moved Strategy Tip: Words can have many meanings Certain words can have specialized meanings when they are used in a specific context. Explain to students that some words have specialized meanings related to occupations. Ask: What does the word cable mean to a television repair person? a telegraph operator? a crane operator? Encourage students to find the multiple meanings for some of the other vocabulary words such as force, groove, and load. You may wish to use Word Study Master Nelson Literacy 4 Teacher s Resource: Pulleys and Gears

3 2. Direct students to read Understanding Reading Strategies with you. Tell them that they will be learning to make inferences while they read this informational explanation. The simplest kind of pulley is a rope or cord pulled over a smooth tree branch or beam. No one knows who invented the pulley, but the first pulley was probably just a rope thrown over a smooth branch. Someone must have discovered that a load tied to one end of the rope was easier to lift. The rope over the tree works because it allows you to pull down in order to lift something up. Pulling down is easier than pulling up because you can use your weight to help you. A wheel at the top works better than the branch because there is less friction and the rope slides more easily. Make It Work! Use a simple pulley to lift a weight. Tie a piece of strong string or cord around a large, thick book. Lift the load with the string using one hand. Now, put the string over the back of a chair and pull the string down with one hand to lift the load. Which way is easier? Ask yourself questions about what the writer has not included. What jobs could have been so difficult that early people invented pulleys to help them? 45 Differentiated Instruction: Extra Support Inferring While Previewing Remind students that to make inferences, they need to think about what they already know and the information the writer tells them in the text. Ask students to look at the illustrations on pages Read the first sentence from the selection: Pulleys and gears are special kinds of wheels. Ask: If pulleys and gears are wheels, what must they look like? (they are likely round) If pulleys and gears are wheels, how do you think they move? (they turn or roll once given a push or pull) What does the illustration on page 45 tell you about when people began using pulleys? (they began using them in prehistoric times) What do you think is in the bag the man is lifting? (food) What can you tell from the illustrations about pulleys and gears today? (people still use them) READING AND DISCUSSING THE TEXT 1. Let students read the first sentence on Student Book page 44. Ask: What are some special kinds of wheels that you ve seen before? (steering wheel, pinwheel, Ferris wheel, hamster wheel) 2. Tell students to read the rest of the text on page 44 and then to read the sticky note. Ask: What do you know about simple machines? (they make it easier to do jobs or tasks) Why are wheels called simple machines? (because they don t have a motor or a lot of parts) How does a wheel make work easier? (makes it easier to move things) Where have you seen wheels used to make it easier to move things? (on a bicycle, skateboard, inline skates, stroller, wagon, scooter) 3. Let students look at the illustration of the men on page 45. Ask: Who are these men? (early humans; prehistoric humans) Why would these men want to hang a bag from a tree branch? (to keep it away from animals) Why would it be easier to use a pulley to lift the bag up into the tree? (it s hard to lift a bag over your head and tie it in a tree) CONTINUED What Are Pulleys and Gears? 19

4 4. Tell students to read the text on page 45 and then to read the sticky note. Ask: What other heavy things might early humans have used pulleys to lift? (building materials, animals, water) How do we use pulleys today to lift these same kinds of materials? (cranes, water wells, pulleys in meat markets) What can you infer about friction based on the following statement from the text: A wheel at the top works better than the branch because there is less friction and the rope slides easily? (friction prevents things from sliding easily) 5. Point out the Make It Work! feature on page 45. Ask: What was your experience when you did this activity in class? Which way was easier?(it was easier to pull the book down than to lift it up) 6. Have students read the first paragraph on page 46 and look at the photograph of the Canadian flag. As they read, remind them to think about times when they ve seen a flag raised. Ask: What would be another way to get the flag to the top of the pole? (climb the pole, use a ladder) How does a pulley make it easier to raise a flag? (you can stand on the ground and get the flag to the top without having to climb up to raise it) Think about your personal experience and clues from the text to draw a conclusion. How would your pedalling be affected if your bike had only one gear? 46 Pulleys and Gears When you raise a flag on a flagpole, you pull down on the rope and the flag goes up. A small, grooved wheel hangs from the top of the flagpole. The flag is tied to a long loop of thin rope that fits into the groove of the wheel. As you pull one side of the loop down, the other side goes up, taking the flag with it. A mountain bike has many toothed gears around the hub of the back wheel. The gears help the cyclist to pedal up and down steep hills. Gear wheels have teeth around their rims. The teeth on one gear wheel fit into the teeth on another gear wheel. When one wheel turns, it turns any other wheel that is linked to it. The gears on a mountain bike allow the bike to go faster or slower while the cyclist pedals at the same speed. Differentiated Instruction: Extra Challenge Making Inferences in Science Point out to students that much of what scientists theorize about the world is based on inferences. They make these inferences based on observations and the data they record based on their observations. Let students challenge their peers inferencing skills by conducting an activity. Give students several plastic film canisters or other nontransparent containers. Have them add to each canister a spoonful of a material, such as dried beans, rice, sand, rocks, salt, or powder. Mark the containers with a number and seal them with tape. Have students exchange their sets of containers with each other. Without opening the containers, challenge students to infer the contents of each container. Discuss with students what sorts of clues they used to try to determine the contents of each container. 20 Nelson Literacy 4 Teacher s Resource: Pulleys and Gears

5 7. Ask students to read the section about gears on page 46 and then read the sticky note. Ask: Visualize your bike in your mind. How many gears does it have? Where do you find them? How do you change gears on your bike? If your bike had only one gear and you started going downhill really fast, how would it affect your pedalling? (there s no resistance in the pedals; you can spin them as fast as you want, but you re not really getting anywhere) If your bike had only one gear and you were going up a steep hill, how would it affect your pedalling? (it s really hard to turn the pedals; even though you push on them really hard, you re going so slowly you might fall over) The writer doesn t tell the reader when to shift gears on a mountain bike. Think about what you know about riding your own bike. If your bike has more than one gear, when do you gear up? (when you are going downhill) gear down? (when you are going uphill) After These questions and activities give students the opportunity to share and consolidate their learning about making inferences. You may use BLM 2: Oral Language Tracking Sheet and BLM 3: Small-Group Observation Tracking Sheet to track student progress through the unit. REFLECTING ON THE STRATEGY 1. Have students reread the title. Ask: Now that you ve read this text, how is the title a good clue for making an inference about what the text is about? (if a title asks a question, I can infer that the text will likely answer the question) How are the illustrations good clues for making inferences about what the text is about? (they provide picture clues that relate to what s in the words of the text) 2. Revisit the strategies for making inferences. Ask: Why is it helpful to think about what you already know and information from the text to help you understand what you are reading? (helps me to connect what I know to what I read so I can make inferences) Why is it helpful to ask questions about what isn t in the text to help you understand what you are reading? (asking questions makes me think about what other things I might know that might help me understand what I am reading) ORAL: DISCUSSING THE TEXT 1. Describe a pulley. (a pulley is a wheel with a groove around the outside for a rope or cable to fit into) 2. Describe a gear. (a gear is a wheel with teeth around the rim that fit into the teeth on another gear) 3. How might life be different if there were no pulleys and gears? (it would be more difficult to lift some objects or to make some things move) 4. Why do you think the informational explanation uses both illustrations and photographs to explain pulleys and gears? (the illustrations show a close-up view of pulleys and gears; the photographs show how pulleys and gears are used) 5. How might you use a pulley or a gear to make some aspect of your life easier? READING: RESEARCHING SIMPLE MACHINES Let students read a variety of texts about other simple machines and their uses. Distribute sticky notes to the students. Ask them to use the notes to mark places in the text where they made an inference by linking what they already know with new information in the text or by asking a question about information that wasn t included in the text. Let them explain their inferences to a partner or in a group. WRITING: INFORMATIONAL EXPLANATION 1. Invite students to write an informational explanation about one of the other simple machines they read about in Reading: Researching Simple Machines. 2. Ask students to describe what their simple machine looks like, how it works, and how it makes work easier. Instruct students to draw an illustration of their simple machine and to find and include a photograph of the machine as it is used in everyday life. Point out to students that the entire piece including the writing should be about one page long. 3. Remind students to include a title for their informational explanation before posting it on a bulletin board. 4. Give students an opportunity to provide feedback for one or two other students using the following prompts. With the clue and what I know about, I think. Based on what I know about, I think that. What Are Pulleys and Gears? 21

6 Word Study Comparative Adjectives 1. Remind students that an adjective describes a person, place, or thing. Tell them that when we compare two things, we are using comparative adjectives. If an adjective is short, we usually add er to it when using the adjective to compare two things. For example, My dog is bigger than your dog. If an adjective is long we usually add the word more or less before the adjective. For example, My problem is more important than your problem. My problem is less important than your problem. Point out to students that this rule doesn t always work. As a final check, they should read aloud their use of a comparative adjective in a sentence. If something sounds wrong, they should figure out how to change it. 2. Have students skim the text for adjectives, list them, and write the comparative adjective beside each one. You may wish to use Word Study Master 2. ASSESSMENT FOR LEARNING Checking Progress Key Assessment Questions Students may respond to the Key Assessment Questions either in writing or orally in a conference. Ask: How did you use what you already know to make inferences? What clues from the text helped you to make inferences? How did asking questions about what the writer did not include help you to make inferences? How did making inferences help you to understand what you read? Record individual progress on BLM 5: Strategy Rubric Strip Making Inferences. Next Steps For students who need extra support with making inferences, use Pulley Power in Student Book 4c, pp for guided reading. For students who understand making inferences, use Pulley Power in Student Book 4c, pp for independent practice. Strategy Rubric Strip: Making Inferences A full-size version of this rubric, suitable for recording assessments, is provided on BLM 5. Criteria Level 1 Level 2 Level 3 Level 4 uses what they already know to make inferences with some uses information from the text to make inferences with some asks himself/herself questions about what the writer hasn t included to make inferences with some explains how making inferences helps the reader to understand the text with some Cross-Curricular Application applies the skills involved in making inferences in other areas of the curriculum with some 22 Nelson Literacy 4 Teacher s Resource: Pulleys and Gears