Simple Machines: Take a Load Off

Transcription

1 Simple Machines: Take a Load Off Grade Level: 3 Time: Three 45- minute blocks By: Keith Barton (Bedford County Public Schools) In this structured inquiry lesson, the students will explore several simple machines and their functions. They will also use a new measurement tool, a spring scale. They will collect and analyze data as they compare the force required to lift a load (a water bottle) without and with the assistance of a simple machine. Students will create a double bar graph to aid with data analysis. Students will investigate the question: How does using a tool affect the amount of energy required to do work? This lesson was developed through the Introduction to Inquiry: A Professional Development Model to Reform Teacher Practices project directed by Science by Inquiry at Sweet Briar College and funded by the Virginia Department of Education Math Science Partnership Grant (MSP) Simple Machines: Take A Load Off Page 1

2 Objectives Know o Simple machines o Force is measured in Newtons o Decreasing an object s weight/mass may decrease force required to move it o Using a simple machine reduces the amount of force required to move an object o Data can be represented in several different forms Understand Do o Students will begin to understand the concept of Force and how it is measured by exploring how simple machines are able to reduce the amount of force needed to move an object. o Measure an object s weight o Collect and analyze data o Represent data in a graph and table format o Learn to use a spring scale to measure force o Explore simple machines Simple Machines: Take A Load Off Page 2

3 Standards Virginia Standards Math 3.17 The student will a) collect and organize data, using observations, measurements, surveys, or experiments; b) construct a line plot, a picture graph, or a bar graph to represent the data; and c) read and interpret the data represented in line plots, bar graphs, and picture graphs and write a sentence analyzing the data. Science 3.1 The student will plan and conduct investigations in which a) predictions and observations are made; b) objects with similar characteristics are classified into at least two sets and two subsets; c) questions are developed to formulate hypotheses; f) mass is measured to the nearest gram; g) data are gathered, charted, and graphed (line plot, picture graph, and bar graph); j) inferences are made and conclusions are drawn; and Science 3.2 The student will investigate and understand simple machines and their uses. Key concepts include: a) types of simple machines (lever, screw, pulley, wheel and axle, inclined plane, and wedge); b) how simple machines function; d) examples of simple and compound machines found in the school, home, and work environment. Simple Machines: Take A Load Off Page 3

4 Context and Background Information This lesson will come at the beginning of the unit on simple machines, and it will be the students introduction to inquiry. The assumption is that few students will have had experiences with an inquiry lesson, so the investigation itself is made relatively simple as a structured inquiry. It will be a springboard for discussions on how simple machines can be found in everyday life and how they can be combined to form compound machines. This will also start the unit on charts, graphs, and data tables, so the math portion is fairly simplistic. There are six simple machines that are included in the Virginia Standards. Four of these will be investigated in this lesson: Lever- A lever is a rigid bar that can be pivoted on a point called a fulcrum. Applying force to one part of the lever will cause a weight (load) somewhere else on the lever to move. Wheel and Axle- This is a wheel with a pole through it. It is used to make objects easier to move over a distance. Pulley- A pulley is a wheel and axle with a groove. A rope or chain is run through the groove. A weight attached to one end can be moved up or down depended on the force at the other end. Inclined Plane- An inclined plane is a ramp. Moving an object up a ramp is generally easier than moving that same object straight up. Two additional simple machines will not be included in this investigation: Screw- A screw is an inclined plane wrapped around a pole. While is can be used to hold objects together, a screw converts a turning force into a linear (up and down) force. Wedge- A wedge is two inclined planes attached back to back. It separates objects by converting a force on its end into two perpendicular forces. The spring scales that came with the kits showed Newtons as decimal numbers, which my class had not yet seen. While I m not 100% sure that they understood the concept, the discussion did lead us into a GREAT conversation about the connections between decimals and money. I will say that despite the problems with the spring scales, they did open a door. The units listed on the spring scales were Newtons, and I had a hard time trying to explaining that to the kids. In the end, I just had to say it was a unit used to measure forces, and since most students hadn t measured forces, they had probably never come in contact with Newtons before. They seemed satisfied, and researching the term and watching a Safari Montage video on Isaac Newton did lead us in an interesting direction once the investigation was completed. Keith Barton Spring scales often display units as both grams and Newtons. Newtons are a unit used to measure forces in this case, it is a measurement of the force of gravity on an object that has mass. As we are on Earth, the force of Earth s gravity on an object is equivalent to the mass of an object, measured in grams with 1 Newton being equal to 100 grams. Of course, Newtons are named after Sir Isaac Newton, the discoverer of gravity. Work is the term scientists use to describe force over a distance. While we often say that work is easier when we use a simple machine, it is actually the amount of force that is reduced. The distance an object has to travel is increased, making the actual amount of work the same. This is a concept that is not introduced until Physical Science, often taught in grade 8. Simple Machines: Take A Load Off Page 4

5 What You Need For the class (or teacher): optional A document camera A projector A few small objects of differing weights <100g For each group: Simple Machines The teacher used the Thames & Kosmos Ignition Series Physics Simple Machines kit. This kit was purchased at a local store for less than $15. This kit included assembly and experiment diagrams and instruction pages. The Instructions pages were a challenge for the students to follow so they would need to be modified if you are allowing the students to assemble the simple machines. Spring scale Filled 8oz. water bottle Graph paper or Graph set- up For each student: An index card Pencil/paper Lab sheet (See Appendices 3-6. When printing the lab sheets, please note that the Investigation Data sheet (Appendix 7) should be copied on the back of all lab sheets.) Spring scales can be purchased from various teacher resource companies for $20-$30 for a set of 6. We suggest clear, tubular spring scales that display the inner workings of the scale and can be read in both Newtons and grams. Simple Machines: Take A Load Off Page 5

6 Getting Ready Before the day of the activity At least one week prior to the start of the lesson: Decide if you will provide the assembled machines or if you want your students to participate in the assembly. If you decide to provide assembled machines, set aside enough preparation time to put each of the kits together. If you are grouping students by interest, you will likely need more of some machines and fewer of others. If you decide to provide instructions and allow the students to assemble, set aside enough preparation time to review and re- write the assembly instructions. Assembly instructions that come with the kits have been found to be very confusing to students. You will want to rewrite the instructions for clarity and reading level. You will also need to put a set of machines together for your own use on Day 1. Two Days Prior to the Start of the Lesson: 1. Give the pre- lesson assessment (Warm- up Activity, see page xx under Appendix). 2. Based upon the pre- assessment, plan for what kinds of support your students may need as they are building their graph during the lesson. The pre- lesson assessment will provide the teacher valuable information about the students readiness to begin the inquiry lesson. At the start of the school year, this engaging hands- on activity will serve as an introduction on many levels. The teacher will get to know the students strengths and challenges; and the students will get to know the teacher s expectations. This is a valuable opportunity for establishing a classroom culture that values student- centered engagement and questioning. Simple Machines: Take A Load Off Page 6

7 Day One: Planning the Investigation Engagement 1. Display and use letters of the alphabet to label (but not name) examples of all six simple machines. A- lever, B- wheel & axle, C- pulley, D- inclined plane, E- screw, F- wedge. Refer to these simple machines as tools. Quickly demonstrate how each can be used by completing a few simple tasks, but avoid telling the students the machines actual uses. As each machine is demonstrated, ask the students to keep a running list of questions and/or observations they may have about any or all of the machines. The wedge and screw will not be explored in this investigation. At the start of the lesson, I showed the class examples of all six simple machines. I played with them and used them to lift loads, move cars, cut paper, and do several other things. This was done to pique the students interest. While this was done, the students observed and tried to give each simple machine a name and a job description. Afterwards, they gave me a list of their top three favorite machines, and that list was used to group the students by interest. 2. Next, write spring scale on the board, and show the actual measurement tool to the class. Stretch the scale under a document camera or as you walk around the classroom. Ask the students what they think might be the tool s use. Discuss the students ideas with the class. 3. After the discussion, tell the class that a spring scale is used to measure force. Most spring scales can have either a metal spring or a rubber band. A large force will stretch the spring a lot, while a small force will only stretch the spring a little. By measuring the distance a spring is stretched, we can measure a force. 4. Demonstrate this idea by using the spring scale to pull two objects of differing weight. Do this under a document camera and draw the students attention to the scale s measurements. This would be a good time to point out that as forces increase, the amount of work it takes to move create that force increases as well. Ask the students if they can use that information to determine which of the two objects took the most work to move. Spring Scales measure force in Newtons, although many also display grams, a measurement of the amount of mass in an object. As we are on Earth, these measurements can be considered equivalent. Newtons are displayed as decimals. If your students have difficulty with decimals, you may need to address that in small groups. Simple Machines: Take A Load Off Page 7

8 5. Explain to the class that in tomorrow s investigation, they will attach a spring scale to the different tools that were discussed at the start of today s lesson. Quickly show the students the tools one more time. You may even want to attach the spring scale to one of the tools as a demonstration. 6. For an exit ticket, pass out an index card, and have each student: Write his/her name Rank his/her top three choices for tools that they want to explore further by writing the tools letters (A- F) on the index card. Try to give each of the three tools a name (based on prior knowledge or an educated guess). Try to name a purpose or use for each of the three tools. 7. Collect these cards. To prepare for tomorrow s investigation, use the students index cards to divide the class into 4 groups of 4-5 students based on interest. Simple Machines: Take A Load Off Page 8

9 Day Two: The Investigation Introduce the Investigation 1. Begin by dividing the students into their investigation groups, based on interest. 2. Tell the students that they are going to conduct an investigation to answer the question: How does using a tool affect the amount of energy required to do work? To set expectations, notify the students that after each group gathers their data, they will report their findings back to the class. 3. Show the class how to attach their spring scale to the water bottle (load) read the measurement, and record the measurement. Likewise, show the students how to attach both the water bottle and the spring scale to each tool (Do not read or record this measurement, but tell the class that there WILL be a place for them to do so on their lab sheets). 4. Give each group their assigned tool and lab sheets (attached). If students are assembling their own machines, allow them time to follow the instructions provided to assemble the machine. 5. Allow the students to conduct their investigation. At this time - tell the students that they are to record their data on the lab sheets provided; however, they are not to complete anything past the solid black like on their lab sheets at this time (questions 5 and 6). The students will run two tests: First, they use their spring scale to determine how much force it takes to lift or pull their load, a water bottle, without the assistance of a machine. Next, they attach the spring scale to their simple machine and lift or pull their load again. Measurements are recorded for both tests, without and with the aid of a machine. This lesson is designed as a structured inquiry: Students are given a question to investigate, they are given the method to follow, and they are provided with the data chart and blank bar graph to fill in according to their data. By providing students with a diagram to build their chosen simple machine, some basic engineering skills will advance, making the lesson more STEM- integrated. Investigation Question: How does using a tool affect the amount of energy required to do work? The students will run three trials of each test and record the results of each on the provided Investigation Data collection sheet. Simple Machines: Take A Load Off Page 9

10 6. While the students are conducting their investigation, the teacher should circulate around the room to ask guiding questions and keep a few things in mind: Things to keep in mind: Make sure that each group has each assembled their simple machines according to the directions that are given. Make sure each student in each group is participating by building, taking measurement, recording measurements, or offering suggestions to their group without always taking the lead. Make sure each student has made a prediction. Possible questions: What kind of differences are you noticing in your measurements? Are you taking your measurements the same way for each trial? How do you suppose people could use this tool in everyday life? This investigation emphasizes that science inquiry is a collaborative endeavor. The social aspects of debate and discussion are an integral part of the nature of scientific inquiry. 7. As an exit ticket for today s lesson, ask the students to answer question number 5, According to your data, what affect did using the tool have on moving the water bottle, on the back of their lab sheet. Simple Machines: Take A Load Off Page 10

11 Days Three: Data Analysis Making Meaning of the Investigation Experience After the investigation is complete, show the students how to make a double bar graph. It is suggested you use the data table from the pre- assessment. Because this is the first time the students will have made a graph like this, it is important to mention each of the following: title, labels for the X and Y axis, determining the scale for the Y axis, listing the trials individually on the X axis, creating a key, and labeling the bars different colors. Next, give each group a sheet of graph paper, and have the students in each group work together to create one double bar graph that shows their investigation data. Once the graphs have been made, present the investigation question one more time: How does using a tool affect the amount of energy required to do work? Have the students look at the bars of their graphs and see if there were any changes when they did/did not use their tool to move the load. Tell the students to quietly discuss what their data show and be ready to present their findings to the rest of the class. The students may also answer questions 5 and 6 on their lab sheet in preparation for their presentation. After the students have discussed in their groups, allow each group to present their graph and findings to the class. Keep each groups graph posted on the board. Wrap Up Begin asking the class how the data on the graphs on the board can be used to answer the investigation question. Explain to the class that the tools that were investigated are actually called simple machines. Simple machines make physical work easier by allowing you to push or pull with less force or in a more convenient direction to move an object. As you point to each graph, reveal the name of the simple machine and its function. Based on your formative assessment of the students understanding, you may end today s lesson by giving the post- assessment. You may want to show examples by logging onto the Simple Machines Website (Gundrum) listed in the references section of this plan. This site shows actual examples of simple machines that can be seen in everyday life. The wedge and screw may take longer to explain since they were not a part of this investigation. Simple Machines: Take A Load Off Page 11

12 Going Further Online Simulations Log on to the Simple Machines (Perkey) website listed on the reference section of this plan. Work your way through The House locating, using, and discovering simple machines in everyday life. With each machine you decide to investigate on the site, make sure to draw the students back to the original investigation question: How does using a tool affect the amount of energy required to do work? Remind the class that the tools are actually simple machines. Simple Machines: Take A Load Off Page 12

13 Assessment Objectives The overall learning objective of this lesson (The Big Idea) is for students to make connections between force and the use of simple machines. Learning goals also include: understanding how to make a double bar graph for comparing numbers, use of a spring scale to measure force (in Newtons); experimental design in the form of multiple trials and treatment/control; graphing and analyzing data to answer an investigation question; and collaboration and communication skills that lead to a deeper understanding of the nature of science. Assessment Plan Knowledge and progress will be assessed in several ways: 1. A short pre- assessment will be given to determine what background knowledge the students are bringing to the lesson. 2. The teacher will take notes on the students work as well as any new questions the students pose as they collect their data. 3. The teacher will grade the groups graph/chart for completeness and accuracy of information. Part of the final grade will also be the students individual explanations of where their data would indicate that simple machines make work easier. The post assessment will determine whether or not the students can name, define, and explain the use of the six simple machines. Pre- lesson Assessment The pre- assessment (labeled Warm- up Activity in Appendix 1) will be used to determine the students readiness for the lesson. It should be completed two days prior to starting the lesson. Questions 1-2 will determine if the students already know what simple machines are and if they can already be named. This information can be paired with their knowledge post- lesson. Question 3 will determine if the students understand that objects with lighter weights may generally take less work to move. Question 4 will help understand the students thoughts on what can be done to make work easier. Will they present a real solution involving machines, extra hands, lightening the weight of the car by removing objects, or if they will come up with ideas that are less realistic. Question 5 will get at the students ability to accurately create a graph. This will help the teacher to know what kinds of support the students will need as they create their own graphs. Simple Machines: Take A Load Off Page 13

14 Formative Assessments: As students are working, the teacher will ensure that the students are on- task and will provide assistance where needed. Listening in on group discussions will help assess engagement and the degree to which students thinking extends beyond the most concrete level. It will also allow the teacher to monitor their collaboration skills. The data collection sheets will reflect students abilities to use spring scales and accurately record data. And the exit ticket on day 2, answer to question 5 on the lab sheet, will help the teacher know which students are able to understand the use of data to answer a question and their ability to link data to a conclusion before the wrap- up of the lesson. Summative Assessments: Student groups will share their findings and discuss their created graphs. As a whole, students will use the data from all groups to answer the question under investigation. Teacher monitoring and notes on the discussion can help to determine the overall success of the lesson. Individual responses to questions 5 and 6 on the lab sheet will help the teacher to identify which students in each group are able to link their data with a conclusion. The post- assessment (Appendix Handout 2) will demonstrate students understanding of the vocabulary and specific content as well as their understanding of how simple machines are used everyday. Overall, the assessment showed me that in a 2-3 days lesson, the students were able to name the simple machines and tell me their uses. That information normally takes two weeks for the science teacher because the kids look at and take notes on one machine at a time. The post assessment showed me that the students were able to correctly match a simple machine with its use. My class did that with 100% accuracy. They were all also able to write sentences that explain that simple machines make work easier. Of course, not all of them used those exact words. Many of them favored the words, They make it easier to do stuff. Keith Barton Simple Machines: Take A Load Off Page 14

15 Acknowledgements Thames and Cosmos. Physics: Simple Machines (Ignition Series). Providence: Thames & Cosmos, Gundrum, C. Simple Machines. Mikids.com Web. June < Perkey, J. Simple machines. Edheads Web. June < machines/> Simple Machines: Take A Load Off Page 15

16 Appendices: Handouts 1. Warm- up Activity 2. Post Assessment 3. Lab Sheet Tool A (Lever) 4. Lab Sheet Tool B (Wheel & Axle) 5. Lab Sheet Tool C (Pulley) 6. Lab Sheet Tool D (Inclined Plane) 7. Investigation Data Collection Sheet Simple Machines: Take A Load Off Page 16

17 Name Warm-up Activity 1. What is a simple machine? 2. Name some simple machines. 3. In each pair, circle the object that would be easiest to lift. Pair 1 Pair 2 Pair3 a desk a chair 10 g 13 g 4. You probably couldn t pick up your mom s car by yourself. What could you do to make that job easier? 5. On the grid to the right, create a graph using the following data: Teacher Boys Girls Mr. Barton 16 8 Mr. Miller Mrs Richardson Mrs. Doss Simple Machines: Take A Load Off Page 17

18 Name Post-Assessment DIRECTIONS: Match a simple from the work bank with it description below. WORD BANK lever inclined plane pulley screw wedge wheel & axle 1. This simple machine is used to separate objects. 2. This simple machine allows heavy objects to move easily across distances This simple machine is used to attach two objects together. This simple machine is used to move up or down slowly. You have to move a greater distance, but the work is easier. 5. This simple machine is sued to raise or lower objects. 6. This simple machine is used to lift or move loads. 7. Write a sentence (or more) that explains the purpose of a simple machine. 8. On the back of this paper, draw a picture of two simple machines that you see in this classroom. After that, label the machines and write a sentence that explains why they are useful. Simple Machines: Take A Load Off Page 18

19 Name Lab Sheet: Tool A How does using a tool affect the amount of energy required to do work? 1. Look at the diagram you were given, and use it to assemble your tool. 2. Predict. a. What do you think will happen when you use you tool to lift the water bottle (load). 3. Move the bottle without the tool. a. Carefully, attach the spring scale to the hook on the water bottle. b. Very slowly, use the spring scale to lift the water bottle straight up until the spring scale no longer stretches. c. Record the measurement in the Trial 1 section of the chart that s on the back of this sheet. d. Repeat this two more times and write the information in the Trial 2 and Trial 3 sections of the chart. 4. Move the bottle with the tool. a. Choose a partner to hold the base on the corner of a desk. b. Set up your investigation as shown in the experiment diagram. c. Pull down on the spring scale until the load is lifted all the way. d. Record this measurement in the Trial 1 section of the chart that s on the back of this sheet. e. Repeat this two more times and write the information in the Trial 2 and Trial 3 sections of the chart. Simple Machines: Take A Load Off Page 19

20 Name Lab Sheet: Tool B How does using a tool affect the amount of energy required to do work? 1. Look at the diagram you were given, and use it to assemble your tool. 2. Predict. a. What do you think will happen when you use you tool to move the water bottle (load). 3. Move the bottle without the tool. a. Carefully, attach the spring scale to the hook on the water bottle. b. Very slowly, use the spring scale to drag the water bottle across your desk until the spring scale no longer stretches. c. Record the measurement in the Trial 1 section of the chart that s on the back of this sheet. d. Repeat this two more times and write the information in the Trial 2 and Trial 3 sections of the chart. 4. Move the bottle with the tool. a. Place the water bottle (load) on the tool. b. Set up your investigation as shown in the experiment diagram. c. Pull on the spring scale until the load is moved across your desk. d. Record this measurement in the Trial 1 section of the chart that s on the back of this sheet. e. Repeat this two more times and write the information in the Trial 2 and Trial 3 sections of the chart. Simple Machines: Take A Load Off Page 20

21 Name Lab Sheet: Tool C How does using a tool affect the amount of energy required to do work? 1. Look at the diagram you were given, and use it to assemble your tool. 2. Predict. a. What do you think will happen when you use you tool to lift the water bottle (load). 3. Move the bottle without the tool. a. Carefully, attach the spring scale to the hook on the water bottle. b. Very slowly, use the spring scale to lift the water bottle straight up until the spring scale no longer stretches. c. Record the measurement in the Trial 1 section of the chart that s on the back of this sheet. d. Repeat this two more times and write the information in the Trial 2 and Trial 3 sections of the chart. 4. Move the bottle with the tool. a. Choose a partner to hold the base on the edge of a desk. b. Hook the water bottle (load) and spring scale together as shown in the experiment diagram. c. Pull down on the spring scale until the load is lifted all the way. d. Record this measurement in the Trial 1 section of the chart that s on the back of this sheet. e. Repeat this two more times and write the information in the Trial 2 and Trial 3 sections of the chart. Simple Machines: Take A Load Off Page 21

22 Name Lab Sheet: Tool D How does using a tool affect the amount of energy required to do work? 1. Look at the diagram you were given, and use it to assemble your tool. 2. Predict. a. What do you think will happen when you use you tool to lift the water bottle (load). 3. Move the bottle without the tool. a. Carefully, attach the spring scale to the hook on the water bottle. b. Very slowly, use the spring scale to lift the water bottle straight up until the spring scale no longer stretches. c. Record the measurement in the Trial 1 section of the chart that s on the back of this sheet. d. Repeat this two more times and write the information in the Trial 2 and Trial 3 sections of the chart. 4. Move the bottle with the tool. a. Choose a partner to hold the base on the corner of a desk. b. Set up your investigation as shown in the experiment diagram. c. Pull up on the spring scale until the load is lifted all the way. d. Record this measurement in the Trial 1 section of the chart that s on the back of this sheet. e. Repeat this two more times and write the information in the Trial 2 and Trial 3 sections of the chart. Simple Machines: Take A Load Off Page 22

23 Investigation Data Without the Tool With the Tool Trial 1 Trial 2 Trial 3 5. According to your data, what affect did using the tool have on moving the water bottle? 6. How might a tool like this be useful in everyday life? Simple Machines: Take A Load Off Page 23