Grabber Using linkages to build a Grabber The
Grabber Using linkages to build a Grabber!
The following documents are for teachers or instructors to facilitate learning with the provided resources.
Teacher Notes Guide What Are Teacher Notes? Each STEM Lab has resources only available to teachers. The goal of these resources are to help you prepare and guide students through each section of the lab. There are two types of teacher resources in each lab: the Teacher section of the lab and teacher notes on pages. The Teacher Section The Teacher section will provide an overview of the lab and resources to prepare for the lab. This section will be very useful to get a big picture overview of the lab and plan class time. The STEM Lab Guide provides an overview of what each section of the STEM Lab is for. The Preview page outlines key information such as materials needed, learning objectives, and standards. In addition, there is a description of each page in the lab. The Pacing guide provides a chart which covers the amount of time, concepts, delivery, materials needed, and resources. The Letter Home provides an introduction to this STEM Lab to let parents know what students will be doing. The Checklist allows you to keep track of how many pages of the STEM Lab have been completed. This could be a useful reference for students as well. The Answer Key provides the answers for the questions in the Know section. Note that the answers will also be provided in a teacher note on that page. The Finding Help page explains how to utilize the kb. vex. com website to answer questions, clear up uncertainties, and have students do their own troubleshooting while completing a STEM Lab. Teacher Notes Teacher notes are sections of teacher-only content which can be found on the pages of the STEM Lab itself. The goal for these teacher notes is to provide in-time tips and guidance for each stage of the lab to make every page easier for you to teach. There are several types of teacher notes which will provide overviews of the content, tips for helping students be successful, discussion questions, extension activities, and answer keys.
There are several main types of teacher notes on the STEM Lab pages: Teacher Toolbox—this type of teacher note will serve a number of purposes. Teacher Toolboxes will have answers to questions or descriptions of investigation results. They could provide additional options for teaching approaches or summaries of the content on the page. Teacher Tip—this teacher note will provide short, direct tips which typically provide justin-time help for making the STEM Lab run as smoothly as possible for students. Motivate Discussion—this type of note provides questions you can ask students to spark discussion and get students thinking about the topics in the lab. Answers, or possible answers, are also provided for guidance.
Extend Your Learning—this note will provide extension activities which can be assigned to students when there is additional time available. Extend Your Learning activities might also be assigned to students who complete their work faster than other students.
STEM Lab Guide STEM Labs follow a sequence of learning experiences. The learner is asked to do the following: Build a device Explore and speculate as to what it does Learn by doing Tinker with the build to improve it Assess learning 1. Seek Each engineering-focused STEM Lab begins with instructions for building a device, model, or structure. Learners should be given ample time to follow the step-by-step instructions for creating the build whether individually or in small groups. 2. Play After creating the build, learners are asked to test what it does. Learners are told to play with the build answer questions about what it does, how it might be used, what if any mechanical advantage it affords, and how to explain the build using engineering terms. Learners are directed to answer these questions within their engineering notebook because the intention is to have their answers be available for review and feedback. The amount of time allotted to this portion of the STEM Lab can vary depending on whether time permits and whether all groups of learners are proceeding at the same rate.
3. Apply The activities within a STEM Lab begin with a brief reading that provides a conceptual context for the concept or skill within the activity. Then learners follow a short procedure for doing something with that conceptual information. Most often, learners will return to testing their builds to recognize some feature of its design, but there are many different types of activities. Some STEM Labs will focus on a single activity by having only one reading and one procedural activity, but most have more than one activity so that multiple concepts or skills can be introduced and more complicated concepts can be explored. At the end of an activity(s), there is an application section where learners are provided with examples of how this information applies to their daily lives and/or to designing/building robots for competitions. 4. Rethink After building and learning about the concepts within the build, learners are given the opportunity to modify the build and explore ways of improving it. Learners are told to answer questions about their modifications in their engineering notebooks and explain and justify the changes they make. Questions are posed to ask about the design phase (#s 1 -3) and the testing phase (#s A-C). The amount of time allotted to this portion of the STEM Lab can vary depending on whether time permits and whether all groups of learners are proceeding at the same rate. 5. Know At the end of the STEM Lab, learners are asked questions about the included information. Questions can be printed if they are to be completed by hand turned in for a grade. Most questions are multiple-choice or true-false. Whether working in team, group, or classroom settings, the answers to the questions can be discussed to make sure that all learners recognize the correct answers and why they are correct. Tips: If the STEM Lab is being used in a classroom or environment with many learners, small groups or teams can be organized to simplify organization and to promote functional collaborations. If all learners are not proceeding at the same pace, a facilitator could extend Apply and Rethink sections for longer periods of time to allow the others to catch up.
If learners are having difficulties completing a build or activity, reference materials within the Appendix section can be used as supplements to guide their efforts.
Grabber Preview 8 - 15 years old 30 minutes - 1 hour, 40 mins. Beginner Description Students will build a device that uses scissor linkages to convert the direction of motion and explore the mechanics of a scissor linkage. Key Concepts Linkage Force Motion Scissor Lift Objectives: Create a build that can alter its size by using scissor linkages. Identify the movement of objects using this build. Identify scissor linkages within professional applications like lifts and explain their ability to convert motion. Apply techniques for strengthening the Grabber's scissor linkages (doubling, crosslinkages, and relocating pivot points). Materials needed: VEX IQ Super Kit Engineering notebook
Facilitation Notes Ensure all required parts for the build are available prior to starting this STEM Lab. Building with some of this build's parts can be challenging. See the Appendix for tips as needed. There is a risk of users being pinched as the Grabber extends and retracts. Anyone handling the Grabber should be careful of its pinch points. An engineering notebook can be as simple as lined paper within a folder or binder. The notebook shown is a more sophisticated example that is available through VEX Robotics. The approximate pacing of each section of the STEM Lab is as follows: Seek - 25 minutes, Play - 30 minutes, Apply - 10 minutes, Rethink - 30 minutes, and Know - 5 minutes. Educational Standards Common Core State Standards (CCSS) RST. 6 -8. 1 RST. 6 -8. 3 Next Generation Science Standards (NGSS) MS-ETS 1 -3
Grabber Pacing Guide STEM Labs are designed to be supplemental education experiences that are flexible and can be implemented in many different ways. Use the Pacing Guide to help make the Grabber STEM Lab fit into your schedule. This STEM Lab can be adapted for a 30 -, 40 -, 60 -, and 55 -minute implementation instead of the full 100 minutes included in the materials. Options for implementing this STEM Lab include: If you have a limited amount of time, only complete the Seek and Play sections. The total time for both sections is 55 minutes. The students will finish with experiences in both building and exploring Scissor Linkage designs. An option for 60 minutes is to have a Grabber (or two) ready before class and have your students complete the Play and Rethink sections. This option compromises the initial building of the Grabber but maximizes gaining experience with the application of scissor linkages and with enhancing the Grabber's design. An option for 40 minutes is to have at least one Grabber ready and have your students complete the Play and Apply sections. Students will gain experience with scissor linkages, while also having a sense of the context and value in learning how linkages and scissor lifts are used in other aspects of daily life. If you have only 30 minutes and can have at least one Grabber ready before class, have your students complete the Play section. Students will gain experience in learning about the scissor linkages within the Grabber's design and begin considering how those linkages change the direction of force. The pacing guide for each STEM Lab provides step-by-step instruction on What, How and When to teach. STEM Lab pacing guides preview the concepts that are taught in each section (Seek, Play, Apply, Rethink, Know) of the STEM Lab, relates the resources that teachers can use to teach those concepts and identifies all of the materials that are needed. The Individual STEM Lab pacing guide contains the valuable information below: Pacing- provides the approximate time duration of each section of the STEM Lab. Concepts- lists themes that surround the STEM Lab. Delivery- provides in-depth guidance on teaching strategies for each STEM Lab section to improve student mastery of the content.
Materials Needed- lists the materials that are essential to completing the STEM lab. Resources- provides the linked content and resources needed by the teacher to complete the lessons and activities. Section Pacing Concepts Delivery Materials needed Resources Seek Building and exploring the Grabber Student Centered 1 or more VEX IQ Super Kits Build Instructions* Cooperative Learning Engineering Notebook Building the Grabber: 20 minutes Exploration: 5 minutes Build Rubric Engineering Notebook Rubric (Individual Reflections) Collaboration Rubric Play The Grabber's Linkages: 15 minutes Converting Motion With Linkages: 15 minutes Apply Where We've Seen Scissor Lifts: 5 minutes Including linkages to convert motion Analyzing the pivot point on the Grabber build Scissor Lifts in a professional environment Designing Incorporating with Scissor a Scissor Linkages Linkage on a Competition Robot: 5 minutes Teacher Direct Instruction Student Centered Cooperative Learning Grabber (built from Super Kit) Engineering Notebook Content Pages "The Grabber's Linkages"* "Converting Motion With Linkages"* “Where We've Seen Scissor Lifts”* “Incorporating a Scissor Linkage on a Competition Robot”
Section Pacing Concepts Delivery Materials needed Resources Rethink Exploring different design features of scissor linkages Student Centered Grabber (built from Super Kit) "Improve the Grabber's Design"* Cooperative Learning Additional pieces from the Super Kit Engineering Notebook Rubric (Team Projects) Improve the Grabber's Design: 30 minutes Collaboration Rubric Applying additional design features to improve the stability of the Grabber Know Review: 5 minutes Summative Assessment* Student Centered * Denotes an essential lesson to the STEM Lab. Multiple Choice Questions Know Questions* Answer Key
Grabber Letter Home Introduction Science, Technology, Engineering and Mathematics (STEM) education presents students with the opportunity to complete hands-on projects that allow exploration of how STEM concepts work together. The following VEX STEM Lab provides an interesting way of exploring simple machines, focusing on levers, by creating a build that uses scissor linkages to the direction of forces and motion. Please keep this letter for your reference as your student works through the Grabber STEM Lab. It contains information that you can use to keep up to date on what students are learning and to spark discussions about STEM and Robotics at home. Look Inside the STEM Lab In this lab, students will have the opportunity to build a Grabber as a team. After recording their reflections on the build in their engineering notebooks, they will learn about the science and benefits of using a scissor linkage within a design. Students will explore the Grabber’s linkage system and how it changes the direction of added force and thereby the motion of the parts of the device. They will then learn about how the scissor lifts used by professionals apply scissor linkage technology. Students will discuss why scissor linkages are often included in competitive robot designs using a variety of gears and brackets. Students will then explore ways to improve upon the Grabber’s stability and overall design by recording their ideas in detailed writing, sketches, testing, and refinement.
Vocabulary Force A push or pull on an object. Linkages An assembly of parts connected to manage force and movement. Motion The process of moving or being moved. Scissor Linkages A type of device that can usually only move in one direction, due to its folding supports in a crisscross "X" pattern. Real World Connection Students will discuss how scissor lifts are used in the workplace by professionals such as mechanics, construction workers, electricians, and warehouse workers. Students will explain how scissor lifts are controlled and allow workers to complete a variety of different tasks at various heights efficiently and safely. Guiding at Home Questions What was the most challenging part about building the Grabber? How can a tool like the Grabber or a Scissor Lift help someone at home or school? How did your group improve the Grabber's design and make it more stable? Did that work? You can explore the STEM Lab at https: //education. vex. com/.
Grabber Checklist Seek o The Completed Look of the Build o Parts Needed o Build Instructions o Exploration Play o The Grabber's Linkages o Converting Motion With Linkages Apply o Where We've Seen Scissor Lifts o Incorporating a Scissor Linkage on a Competition Robot Rethink o Improve and Tinker with Your Build Know o Review Appendix o Removing Pins from VEX IQ Beams and Plates o Removing Connectors from Beams and Plates
Grabber Answer Key Teacher Toolbox Answer Key: The scissor linkage used for the Grabber will: Cause a transfer of motion. When adding more linkages to the Grabber, it will: Increase the distance it can extend but decrease its stability. Which of the following professions is NOT likely to use a scissor lift? Restaurant worker When designing a scissor lift for a competition robot, which of these is most likely to be used with the scissor lift? A motor
Finding Help VEX Robotics offers support documentation mostly in the form of "How to" articles to help new users get quickly up and running and to help more experienced users find timely and targeted answers to their questions. The articles are particularly helpful when running STEM Labs. If you find yourself uncertain of how to do something, the VEX Robotics Knowledge Base likely has an article to help you with it. The link to the VEX IQ section of the VEX Robotics Knowledge Base is kb. vex. com. On the landing page, click on the large VEX IQ button to see only that portion of the knowledge base. The Search bar can be used to find specific articles from the entire database. For example, you or a student might have questions about charging, installing, and any other information related to batteries. To search for all articles related to VEX IQ batteries, use the search terms "IQ Battery -V 5. " This search returns any article related to the VEX IQ Robot or Controller Batteries and excludes any term related to V 5.
Articles are continuously added to the database. Topics range from installing hardware to installing programming software, and from navigating the VEX IQ Robot Brain to reading indicator lights. There also troubleshooting articles ranging from fixing displayed error messages to troubleshooting VEX IQ Smart Motors. Links to knowledge base articles are also provided within the text of this STEM Lab. For example, if the reader is asked to "Use the Autopilot program. . . , " the first time the word "use" is written it is likely linked to the knowledge base article "How to Use the Autopilot Program in the Demos Folder. " The best times to use the VEX Robotics Knowledge Base are when: You are planning a STEM Lab or preparing a learning environment. Students are independently investigating and solving their own problems related to hardware, software, or programming. You and your students are troubleshooting together.
Discover new hands-on builds and programming opportunities to further your understanding of a subject matter.
The Completed Look of the Build Teacher Toolbox - The Purpose of this Section The purpose of this STEM Lab Seek section is to give students experience building the Grabber to explore converting motion with linkages. Understanding motion is important in Robotics or other disciplines that would require an object to extend, lift and move efficiently. Students will explore scissor lifts and how tall structures overcome gravity by maintaining stability. Students will also explore incorporating a scissor linkage on a competition robot. A completed build of the Grabber
Teacher Tips Use this image as a point of reference to verify if students constructed the Grabber correctly and to provide students with a preview of what they are about to build. Allow students enough time at the end of the class period to note where they left off in their engineering notebooks and clean up their area. Linkages convert input force or motion into a different output force or motion. There are several types of linkages. The Grabber build uses a scissor linkage to show a simple design can transfer motion. Teacher Toolbox The Seek section of the STEM Lab guides students through building the Grabber needed for the rest of the lab to explore the concept of motion. If you or your students have already built this Grabber and have gone through the questions on the Exploration page, you can skip down to the Play section of this STEM Lab and continue from there.
Build Instructions Teacher Toolbox The build instructions will show students step-by-step instructions on how to build the Grabber. The Build Instruction Tips section will point out additional information for specific steps which will help students be successful with their build, so be sure to point out that section to students. There is an optional rubric to evaluate the build on this page. If any rubrics are used to evaluate students, review the rubric or pass out copies before students begin working so they are clear on how they will be assessed. Before starting the build, consider how your students will be organized. Will each student have their own mechanism, or will they work in pairs or teams? If working in teams, each student could build a portion of steps or each student could be given a role. If students are working in groups, there is an optional collaboration rubric on this page. For suggestions on dividing the build components among the students on a team, click here. Teacher Tips There are many common part types students will engage with as they build with their VEX IQ Super Kit. Students may use the VEX Super Kit Contents and Build Tips Poster (included in their kit) to assist them with their build. Instruct students to take apart pieces by gently rotating and pulling off carefully in order to not disturb the rest of the build or damage pieces.
Build Instruction Tips All Steps: There is important information about which parts are needed for the step above the partition line. The number below the image of a part is the number of that part required in the step. There may be dimension information below the part to help identify which size to use. Step 1: Count all pieces before starting your build and have them readily available. Step 7: Insert 1 x 1 Connector Pins into the first and seventh hole in the 1 x 8 Beam. Step 9: Inter the 1 x 1 Connector Pins into the 1 x 8 Beam first, before attaching the 1 x 6 Beam. Pinch Points: Be careful when attaching pieces, removing pieces, or manipulating the Grabber that nothing will be pinched in movement.
Extend Your Learning – Sammy Who is Sammy? Sammy is a VEX Robotics companion made out of only 9 VEX IQ pieces. Sammy is a great extension learning activity because students can create any accessory or setting for Sammy that they like. Students are only limited by the bounds of their imagination! Click this link to see the build instructions for Sammy. Ask students to build a Sammy when they have finished the build early, or as a fun, stand-alone extension activity. If students have already built a Sammy in previous labs, ask them to play a claw game with Sammy. A possible idea is asking the students to compare what objects can be picked up with the Grabber in a claw-like fashion. Pose questions to the students such as, “What do you notice happening to the Grabber when you try to pick up a heavier object compared to a lighter one? What do you think could happen to the Grabber if you extended it even longer by adding more Beams? What would be the result if the Grabber were made of thin cardboard instead of plastic? ” Ask the students to write down their findings in their engineering notebook. There is also the option to use the engineering notebook as an assessment. Click this link to see the rubric for an engineering notebook.
Exploration Teacher Toolbox Students can explain how the Grabber can grip, lift, move, and release an object. Possible answers include using the Grabber as part of a new game or helping handicapped individuals reach items that they may need. Yes, the Grabber contains several levers that give the user a type of mechanical advantage called distance advantage. The "advantage" occurs when the levers magnify the force exerted when applied and increases the distance the Grabber can move. A possible example of an answer could be "The Grabber is made up of several levers; a type of simple machine. Beams and connectors are required to form its structure. The beams that make up the levers are connected at a pivot point, or fulcrum, with a connector. The beams and connectors work together to create a distance advantage. " Now that the build is finished, explore and see what it can do. Then answer the following questions in your engineering notebook: What does the Grabber do? Explain with details. How might the Grabber be used? Explain with details and sketches. A mechanical advantage is an advantage gained by the use of a mechanism in transmitting force. Does the Grabber have a mechanical advantage(s)? If so, what is the mechanical advantage? Explain with details. Explain this build, using common engineering terminology, to someone who hasn't seen it. Use at least 3 of the following terms in your description: beams, connectors, levers, pivot points, fulcrum, and simple machines. For example, I could say that beam is an engineering term that describes this build because the build requires beams to form its "structure. " You may need to look up these terms if you need clarification.
Teacher Toolbox Advise students to think critically about the questions by engaging in thinkpair-share. To do this, have the students answer the questions themselves in their engineering notebook. The engineering notebook can be used as assessment. Click this link to view the engineering notebook rubric. Then after a few minutes, have the students turn to a partner or a group of three students to discuss what each student has written. Encourage them to reflect on different answers that their peers provide. Collaboration can also be a form of assessment. Click this link to view the collaboration rubric. Finally, after another few minutes, open the class up for discuss to obtain a more critical analysis of the questions.
Test your build, observe how it functions, and fuel your logic and reasoning skills through imaginative, creative play.
The Grabber's Linkages Teacher Toolbox - The Purpose of this Section The goal of the Play section is to allow students to test the build and help them explore converting motion with linkages. Allow the students to test how the Grabber moves. The Motivate Discussion section provides questions to get students thinking about how scissor linkages change the direction of a force and how the Grabber's build could be improved. The second page of the Play section will introduce scissor linkages used within professional scissor lifts to provide another familiar context for analysis. When working in groups, the following student roles can be assigned: Build Expert: Responsible for understanding the Grabber's structure and demonstrating the build's operation at different points during the activity. Recorder: Responsible for documenting feedback from the entire team within the engineering notebook. If groups are larger than two, more than one student can share the responsibilities of the same role. A team-based engineering notebook rubric is available by clicking here and a collaboration rubric is available by clicking here. For a rubric to score individual engineering notebooks, click here.
1. Examine the Grabber In Step 2 of the Grabber build, you created a linkage by attaching two beams together at the center using a pin. This created a scissor linkage. That should be easy to remember when you think of how the sides of scissors move around a center point. Build Expert: hold the ends of the bottom two beams in each of your hands. Close and open the Grabber by moving your hands apart and back together again, similar to using a single pair of scissors but with two hands. Recorder: sketch and explain in your engineering notebook how the Build Expert's movements compare to the movements of the Grabber. Compare the direction of each beam's movements and identify a pattern. Hint: Look at how the pins affect the beams' movements. Teacher Toolbox - Answers The pattern to notice is that as the Build Expert moves the ends of the Grabber closer and farther apart, the pins act as pivot points and the beams move inward and outward, respectively.
2. Consider Extending the Grabber The Grabber has three scissor linkages. Adding more scissor linkages would allow the grabber to lift or extend further. Build Expert: place the Grabber down so that it is halfway opened. Consider how much longer the Grabber would be if two more scissor linkages were added to the build. You can use the length of the two bottom beams to estimate. Recorder: sketch what the extended Grabber build would look like. Explain why adding two more scissor linkages might not be a good design plan. What could change about how the Grabber works if two more linkages are added to the build? Teacher Toolbox - Answers Adding two more scissor linkages would change how much force is needed to control the Grabber and would decrease the stability of the build. The longer Grabber would require more force to push out or pull in. The added weight would also put more stress on the beams and especially the pins and therefore, decrease its stability.
Motivate Discussion Q: When the user pushes the ends of the Grabber's handles together, does the grabbing end move closer together (pinch) or move farther apart (open)? A: The grabbing end moves closer together (pinches or grabs) when the user moves the handles closer together. Q: Does the force created by pushing or pulling the Grabber's handles always move in the same direction or does it change directions? If it changes directions, where does the force change directions? A: The force created by pushing or pulling the Grabber's handles changes directions several times each at pivot point or pinned connection in the build. Q: As further linkages are added, how can you improve the build to make it more rigid and stable? A: One possible solution is to use thicker beams to provide more stability (a 2 x 4 Beam instead of a 1 x 4 Beam would be an example). Another possible solution is to use longer pins (a 1 x 2 or a 2 x 2 instead of a 1 x 1 Connector Pin).
Extend Your Learning To expand this activity, explain to the students that a simple lever is an example of a two-bar linkage like a scissor linkage. The ground is considered one link connected at a joint, or fulcrum, to the lever. In the scissor linkage, there is not a joint created by a fulcrum but a pivot point created by a pin. Have the students explore more complex linkages and record their designs/details in their engineering notebooks. Some examples of more complex linkages are: Binary Link Ternary Link Quaternary Link Pentanary Link
Converting Motion With Linkages A scissor lift Converting Motion With Linkages are a fundamental part of how machines are designed because of their ability to create such a wide variety of output motion. Linkages can also change the direction of a force. The picture above shows a scissor lift which uses multiple scissor linkages. A scissor
lift is often used to raise or lower people. In order for a scissor lift to raise, force is applied to the outer beams at the bottom of the lift. As force on the beams at the bottom pushes them closer to the center, the lift raises. This is a great example of how a linkage can change the direction of a force. In this case the linkage was again a scissor linkage like the Grabber's, but the force was generated by a motor instead of by the user squeezing the bottom beams. Build Expert: explain how a platform might be added to the top of the Grabber to create something similar to a scissor lift. Recorder: sketch and explain the design you decide on in your engineering notebook. Teacher Toolbox - Answers may vary, however, the students should note that a larger plate could be attached to the top of the Grabber. A 4 x 12 Plate from the VEX IQ Super Kit could work as a stable platform. The students should also note that the platform cannot be mounted directly to the ends of the Grabber. If it were, the Grabber would no longer be able to move. As the Grabber extends, the tips of the Grabber move closer and closer together. Thus, it would be optimal to have the tips of the Grabber in some sort of track where they can continue to move freely without compromising the platform. Extend Your Learning - Linkages are like Levers To expand this activity, draw the connection between linkages and levers presented on the previous page. Then have students investigate some astonishing uses of simple levers - like the construction of some of the most imposing structures built by humans in ancient times: the Egyptian pyramids. Students can research the Pyramid of Khufu, also called the Great Pyramid of Giza. It was the tallest man-made structure (over 480 feet tall) for over 3800 years and one of the Seven Wonders of the World. The Egyptians used several simple machines, including levers, to move 2. 3 million blocks of rock weighing 5. 9 million tons to create this remarkable structure. Ask students to research how the Egyptians used the simple machines like levers to move the heavy materials. Instruct students to write their observations in their engineering notebook.
Conclusion Conclude this lesson by engaging the students in a whole-class discussion. Ask the students to share their thoughts on linkages and scissor lifts in order to summarize what they have learned from this activity. Encourage students to share their comments from their engineering notebooks.
Become a 21 st century problem solver by applying the core skills and concepts you learned to other problems.
Where We've Seen Scissor Lifts Teacher Toolbox - The Purpose of this Section This Apply section will help students understand how converting motion with linkages is used in the real world by analyzing scissor lifts. The questions on this page can be explored as a group by facilitating a class discussion or individually having students write their ideas in their engineering notebooks. This can be used as a summative assessment such as a homework assignment or in-class formative assessment. Click this link for the engineering notebook rubric and this link for the collaboration rubric. The Motivate Discussion section provides questions to get students thinking about in what situations scissor lifts or linkages in general can be useful. A scissor lift being used for construction
Reach For the Sky! The Grabber and the scissor lift are very similar devices. Scissor lifts are used in many different professions. They allow workers to reach a variety of different heights as they complete their jobs. In addition, scissor lifts offer a mobile and stable platform to complete work from. They are often used in place of ladders or scaffolding. Their mobility, as well as their stability and security, create a safer and more efficient work environment. Some of the professions below frequently use scissor lifts: Construction Workers Electricians Carpenters Warehouse Workers Mechanics
Motivate Discussion Scissor lifts are seen in the majority of major cities as well as construction sites and are helpful in making work environments more stable, safe and secure. Prompt your students to discuss how scissor lifts can be useful. Q: What is the benefit of using a scissor lift compared to a ladder? A: A scissor lift can usually extend further and remain more stable even when there are external factors such as wind or slight shaking. A ladder also requires a structure for it to lean on, while a scissor lift can raise vertically in the air without depending on another structure to be close by. This can be helpful when fixing power lines or other situations where the area of interest might be isolated. A ladder also usually only has the capacity to support one person at a time, while a scissor lift usually has a platform on the top that can support multiple people at once. Q: Linkages can be used to create mechanisms such as the Grabber or scissor lifts, which can extend vertically (straight up) or horizontally (outwards). Are there other types of linkages that could enable mechanisms or robots to move? A: Yes. A possible answer can be the four-bar linkage, which would allow a robot to raise and lower an arm or other device in an up and down elevator fashion. Q: What could happen to the Grabber if more links were added to allow it to extend longer? A: The Grabber could extend longer but also require more force to extend it as additional sections were added. It would also potentially become less and less stable the more links (Beams) that are added without reinforcing the rest of the design. If more Beams are being added, more 1 x 1 Connector Pins may need to be added as well to help reinforce the structure. Another option may be to use a stronger material such as steel. Q: Scissor linkages are not only used for lifting. They are also commonly used for extending over a space or retracting to their compact forms on the side of a space. Where might you have seen a scissor linkage being used to extend over a space? A: The best example is a scissor gate that is used for remaining compact while also being able to extend over a space. Some of the most common places to see scissor gates are at the tops of stairs in home with animals or young children, on storefronts as added security, in airports, or in old elevators.
Extend Your Learning To expand this activity, try the following: Have students work in groups to find pictures online of scissor lifts in use and then create a collage of these simple machines. Students can label each example with the profession in which it is used. Another option for this activity would be to build a scissor lift out of a different material such as cardboard. Cut out rectangular pieces of thin cardboard and connect them in the same design as the Grabber using push-pins or thumbtacks as the connecting pieces like the 1 x 1 Connector Pins. Experiment with different sizes of rectangular cardboard pieces. Instruct students to reflect on different designs by comparing and contrasting materials in their engineering notebook.
Incorporating a Scissor Linkage on a Competition Robot Teacher Toolbox This page will inform students of the possible benefits that scissor linkages can have on competition robots. Before reading this page, have students brainstorm when it could be beneficial to design a robot with scissor linkages and write these ideas in their engineering notebooks. Once students have written down their ideas, read through this page as a whole-class. The VEX IQ build featured in the image is one example of using scissor linkages with the addition of a motor to power the lift. Because it is immobile, this example is not competition-ready but this one was chosen to highlight adding a motor to a Grabber-like device. Use the Motivate Discussion questions to get students thinking about other applications of scissor linkages for their robots.
A motorized scissor linkage Designing with Scissor Linkages You can use a scissor linkage in your design when you need to change the shape and size of your robot to accomplish a specific task. Scissor linkages are often included in robot designs with Rack Gears and Linear Slide Brackets so that their motion can be controlled by a motor. This can be useful when it comes to designing a robot for competitions. A scissor linkage is helpful in many robot applications. A scissor linkage can be used to increase a robot's height. If your robot needs to start compact, but stretch out horizontally, you can use a scissor linkage to increase its width.
A scissor linkage can extend a robot's reach if the robot needs to pick up objects and then place them in different locations. Motivate Discussion Q: What do you think the motorized scissor linkage in the photo does? A: It likely grabs or pinches something like the Grabber does but is powered by a motor. Q: Do you think a robot like this is likely to win a competition? A: It depends on the game but generally, this robot cannot drive around or do much other than pinch. So, it seems unlikely to score many points. Q: Besides a chassis with a drivetrain, what else could be added to this scissor lift in order to make the robot more competition-ready? A: Answers will likely vary but one of the best responses is likely that a platform could be added to the top of the lift. This would allow game objects or other parts of the robot to be moved up and down as needed. Other answers might include better ends for pinching and holding or a better base that would allow the scissor linkage to grab, hold, and move an object. Q: How would you use a scissor linkage on a competition robot? A: Answers will likely take inspiration from the three applications listed on this page and that is intended. Have students add their own details about how the linkage would function and how that would be a benefit to the robot's design. Extend Your Learning To expand on this activity, think about what type of game elements would be the easiest and most difficult to pick up and move with a scissor linkage. For some examples of actual competition game elements, visit the VEX website to see the current game elements and past game elements. To connect this activity to robotics competitions, ask students to join a robotics competition team. More information about this year's competition can be found at the Robotics Education & Competition Foundation (REC) website. The VIQC Hub app is also available for download and is the ideal competition companion for teams, spectators, and event planners involved in the VEX Robotics Competition! See more information about and download the app here.
Conclusion Conclude this section by engaging students in a whole class discussion. Ask students to share their thoughts on the value of scissor linkages on competition robots and summarize what they have learned from this section. Encourage students to share their comments from their engineering notebooks.
Is there a more efficient way to come to the same conclusion? Take what you’ve learned and try to improve it.
Improve the Grabber's Design
Teacher Toolbox - The Purpose of this Section The next two pages will allow students to think about how they would change the build. On the first page, examples of enhancements (doubled lifts, crosslinkages, and different pivot points) are provided as introductions to how the Grabber could be structurally and functionally improved. Making those improvements will require extra parts from the Super Kit. A list of parts for each design is provided within the Appendix so that the additional parts can be assembled before beginning. Note: The Cross-support example is constructed with six 1 x 12 Beams but the Super Kit only includes four. One solution to this is to apply the same technique but with shorter beams (e. g. , 1 x 8 Beams) which will not affect the design. Allow students time to review the presented enhancements. If time allows, you could facilitate a class discussion of these different types of enhancements, which pieces from the kit are involved, and how these enhancements might be integrated into their Grabber builds. The second page will ask them to design and plan their improved Grabber by independently answering questions and sketching in their engineering notebook. The questions could be used as a summative assessment such as a homework assignment or a formative assessment by facilitating an in-class discussion and having the students reflect on the questions in their engineering notebook. Click this link for the engineering notebook rubric and this link for the collaboration rubric. Of course, many of the students' ideas for changing the build are likely to be informed by the example enhancements and that is okay. This is a introduction to engineering and design. They should apply tested and recommended techniques like those in the examples to build experience in common solutions to structural problem solving. Success on this challenge should not depend on whether the students can be creative and/or innovative but instead focus on how well students are able to plan to make the changes to the build. Think about your experience using the Grabber. Review each of these techniques for building a better Grabber.
As you review each, consider whether your Grabber would be better if you used the engineering technique described to change your build. Technique: Doubled-up Explanation: Beams are at least doubled so that the Grabber is more rigid and will not bend when picking up heavy objects. Changes to current Grabber: o Shorter in length and fewer pivot points o All beams are doubled and connected to each other with pins o Collared shafts and rubber shaft collars are used as pivot points (Red arrows show where) Parts added: o 1 x 8 Beam (Quantity: 2) o 2 x Wide 2 x 2 Corner Connector (Quantity: 1) o 3 x Pitch Plastic Capped Shaft (Quantity: 3) o 4 x Pitch Plastic Capped Shaft (Quantity: 1) o Rubber Shaft Collar (Quantity: 4) o 1 x 2 Connector Pin (Quantity: 4) Parts removed or replaced:
o 2 x Wide 1 x 2 Offset Corner Connector (Quantity: 1) o 1 x 1 Connector Pin (Quantity: 1) Teacher Tips - Understanding the Changing Parts Students might be confused about what the "Parts added" and "Parts removed or replaced" sections are telling them for each change to the Grabber's build. "Parts added" tells the students which additional parts they will need from the kit. These are in addition to the Parts Needed that were listed for the original build. So if they started with one of these parts included in the original Grabber build and here it also says they need one additional part, then they will need two to complete this build. "Parts removed or replaced" tells the students that these parts are no longer included in this example build. They may have simply been removed because they didn't fit into this new design, or they may have been replaced by another part that made more sense for this design. The Teacher Toolbox at the bottom of this page provides each new Grabber's parts list. Technique: Offset-center Explanation: The pivot points are positioned where they don't make the Grabber open too much or too little.
Changes to current Grabber: o Shorter in length and fewer pivot points o Pivot points away from center to a location where they work best (Red arrows show where) Parts added: o 2 x Wide 2 x 2 Corner Connector (Quantity: 1) Parts removed or replaced: o 1 x 6 Beam (Quantity: 2) o 1 x 12 Beam (Quantity: 2) o 2 x Wide 1 x 2 Offset Corner Connector (Quantity: 1) o 1 x 1 Connector Pin (Quantity: 7) Technique: Cross-support Explanation: Pivot points are reinforced so that they are stronger, which makes the Grabber more rigid, stable, and strong. Changes to current Grabber: o Shorter in length and fewer pivot points o The beams with center pivot points are reinforced using another beam of the same size and standoffs (Red arrows show standoffs) o Added beams require longer pins Parts added: o 2 x Wide 2 x 2 Corner Connector (Quantity: 1) o 1 x 12 Beam (Quantity: 2) o 1 x 2 Connector Pin (Quantity: 6)
o 1/2 x Pitch Standoff (Quantity: 4) Parts removed or replaced: o 1 x 6 Beam (Quantity: 2) o 1 x 8 Beam (Quantity: 2) o 2 x Wide 1 x 2 Offset Corner Connector (Quantity: 1) o 1 x 1 Connector Pin (Quantity: 13)
Plan Your Grabber's New Design Teacher Toolbox The questions on this page have students think about their design for the new Grabber, the plan for creating it, and the benefits of the modification. This activity is less about perfecting the Grabber build and more about getting students to decompose the problem of improving it, consider techniques for improving it, plan out a way to change it, and explain or justify why this proposed change is worthwhile. That should all be included within their engineering notebooks. Click either for an individual engineering notebook rubric or a group-based engineering notebook rubric, as is appropriate. Be sure to share the rubric prior to having the students begin answering these prompts. Answer the following questions in your engineering notebook: What do you want to change about the build by using other pieces in your VEX Super Kit? Explain at least two changes and name the technique(s) being applied if you are using one of the previous examples. What parts will you use to change the build? List the names of all needed parts and how many of each part the build requires. Create your own set of Build Instructions for your new Grabber design so that someone else could follow them to make their own Grabber. Start at Step 1 because the person might not have a Grabber yet. Explain with details and/or sketches. How do your changes to the Grabber make it better? Explain with details and/or sketches.
Teacher Toolbox - Answers Students' proposed changes can be as creative as the teacher allows but they should demonstrate consideration for the functionality of the Grabber and the available pieces in the VEX Super Kit. The proposed changes shouldn't simply be aesthetic or idiosyncratic but instead increase the functionality of the Grabber. Also, the proposed changes to the build need to be possible with the parts still available in the VEX Super Kit, after the Grabber is built. Students can communicate their proposals in text or drawings. If students are proposing doubled-up beams, cross-linkages, or off-center pivot points, then be sure they recognize how they are related to the examples provided on the previous page. Students might start by creating a list of the parts they want to add to the Grabber build, a list of the parts they want to remove, or some smaller list of parts that can start this process. Then they can compile only the parts they need into a single list for their build. It is recommended that students list all of the parts listed, including those that remain from the original Grabber build. Students should be able to communicate the steps of their changes and the parts used in a logical manner by either text or drawings in their engineering notebook. The build should start at Step 1 and guide a user through building this improved Grabber to completion. Students should be able to explain why their proposed changes improve the Grabber. Possible explanations could include increasing the Grabber's extension in order to give it a farther reach, reducing the Grabber's extension in order to improve stability and to have the Grabber bend less, improving the Grabber's handles so that users have a better grip, or making the linkages more rigid and strong to properly handle heavier loads/objects.
Extend Your Learning - Carrying out the Building Plans User-Testing the Build Instructions: If time permits, allow the students to swap build instructions with a classmate. Each student will then follow another's Parts Lists and Build Instructions in an attempt to test how well they plan the build. Students can take notes in their engineering notebooks about which step(s) of the instructions were confusing, if any. User-Testing the Improved Grabber: Students who are successful in completing the new Grabber build should then test it and compare its strength, rigidity, and extension length to the original Grabber's to determine if it is indeed improved. They can rate each of the three dimensions in their engineering notebooks. An original Grabber might be around so that they can test both versions at the same time. Documenting User-Feedback: Students can then report back to the designer and find out if the improvements found in testing match the improvements planned. The designer can note whether the new design was successful in reaching its intended improvements to the build. The collaboration rubric could be used to score this activity - if desired. The rubric related to the build is not appropriate because the build is only in a testing phase.
Understand the core concepts and how to apply them to different situations. This review process will fuel motivation to learn.
Review Teacher Toolbox - The Purpose of this Section The Know section will conclude the Grabber STEM Lab and allow students to demonstrate their knowledge of the concepts presented in the activities. Allow students time to independently answer these questions. Another option would be to use these questions as a summative assessment such as a homework assignment or a formative assessment as an in-class activity. If time allows, have the students reflect on the questions in their engineering notebook independently or facilitate a whole class discussion. Click this link for the engineering notebook rubric and this link for the collaboration rubric. Teacher Toolbox Answer Key: The scissor linkage used for the Grabber will: Cause a transfer of motion. When adding more linkages to the Grabber, it will: Increase the distance it can extend but decrease its stability. Which of the following professions is NOT likely to use a scissor lift? Restaurant worker When designing a scissor lift for a competition robot, which of these is most likely to be used with the scissor lift? A motor 1. The scissor linkage used for the Grabber will: o Pivot through a complete circle. o Cause a transfer of motion. o Cause the end of the Grabber to stay in one location. o Provide a rigid (non-moving) connection. 2. When adding more linkages to the Grabber, it will:
o Increase the distance it can extend but decrease its stability. o Increase the distance it can extend and increase its stability. o Decrease the distance it can extend and decrease its stability. o Decrease the distance it can extend but increase its stability. 3. Which of the following professions is NOT likely to use a scissor lift? o Carpenter o Warehouse worker o Restaurant worker o Electrician 4. When designing a scissor lift for a competition robot, which of these is most likely to be used with the scissor lift? o Weaker connection points o A motor o Rubber belts o Pulleys
Additional information, resources, and materials.
Parts Needed: Doubled-up Grabber
Quantity: 2 Quantity: 4
Parts Needed: Offset-center Grabber
Quantity: 2
Parts Needed: Cross-support Grabber
Quantity: 6 Quantity: 2
VEX Robotics Knowledge Base Articles Links to Knowledge Base articles for this STEM Lab: Ideas for Organizing the VEX IQ Super Kit How to Get Started with the VEX Plastic Construction System How to Decide on which VEX Plastic Connectors and Standoffs to Use How to Select, Capture, and Support VEX Plastic Shafts How to Decide on which Beam, Specialty Beam, or Plate to Use Glossary Force A push or pull on an object. Linkages An assembly of parts connected to manage force and movement. Motion The process of moving or being moved. Scissor Linkages A type of device that can usually only move in one direction, due to its folding supports in a crisscross "X" pattern.
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