Explain how the muscles and bones of the human body function together as levers. Justify categorization of lever types.

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PHYSICAL THERAPY Essential Question: How Is the Body Like a M achine? Learning Targets: Students will: Explain how the muscles and bones of the human body function together as levers.

1 PHYSICAL THERAPY Essential Question: How Is the Body Like a M achine? Learning Targets: Students will: Explain how the muscles and bones of the human body function together as levers. Justify categorization of lever types. Lesson Overview Biomechanics is the application of the principles of mechanics (physics) to the living body. The body s skeletomuscular system is comprised of levers that give it mechanical advantage when working with the force of gravity to produce movement. Physical therapists understand these principles and use them to rehabilitate injuries so that people can experience normal range of motion in their joints and movement that is not compromised. In this lesson, YPs will explore the action of levers and how the body is made up of many levers. 1

2 Lesson Agenda Opening (10 min) Emergency Scenario: Rehabilitation (10 min) Work Time Biomechanics: An Exploration in Levers (20 min) Lever Vocabulary Basics (5 min) Muscle Density Activity (20 min) Closure (5 min) Careers in Biomechanics Materials: Young Allied Health Professional student packet Modeling the arm as a lever activity (one per pair of students) <How Is Your Arm a Lever?> procedure Table Bucket with a strong handle Sand or other material to put in the bucket Categories of types of levers (one per group) Lever example cards (one set per group) Lever vocabulary post-its (one set per group) Rubber bands with various widths Rulers (w/ centimeters) FACILITATION NOTES The Narrative Arc. The more each <Emergency Scenario> can be presented as if telling a story, the more engaged the audience will be. Work to avoid a stale reading and lean towards bringing the information to life as in a conversation or a reveal of the next chapter. Think of creative ways to make the story your own. Partners. Students are very active in this lesson. Be sure they change colleagues and work with different students throughout. Background Information on Levers. Need a review of levers? See this 12 minute video at: 2

3 Optional Videos: The Mighty Mathematics of the Lever. Breaks down the parts of a lever. Animated but advanced, illustrates see-saw as a lever with multiple examples: Building Lever Models. Invite students to build the three types of levers and see simple machines in action: Levers/dp/B003DKJEC4/ref=sr_1_2?s=toys-and-games&ie=UTF8&qid= &sr=1-2&keywords=levers. Extensions Muscle Density. As an extension to this activity, consider exploring fast vs. slow twitch fibers ( as well as voluntary vs. involuntary muscles in the body ( IN ADVANCE Have a device available to project instructions. Review the Card Sort protocol. Review the Biomechanics Challenge Questions (for teacher reference). Vocabulary Content biomechanics, fulcrum, effort, load, external, internal, muscle density, muscle fibers Tier II categorize, range, effort Opening (5 min) Even after injuries, like broken bones, have been fixed and are healing, patients often need a physical therapist to help them experience less pain and to regain some of the freedom they should have in their movement. 3

4 Emergency Scenario: Rehabilitation 1. Ask: Have any of you or anyone you know needed physical therapy for any reason? 2. Invite volunteers to share their experiences. 3. Ask: Does anything from science come to your mind when you hear the term biomechanics? 4. Invite volunteers to provide answers. Listen for: bio like biology. Mechanic. Simple machines, levers, force, etc. If the young professionals do not know, assure them that in this lesson they will be learning about how the body uses simple machines, like levers, to move. 5. Share the <Emergency Scenario: Rehabilitation> in a conversational, engaging way. 6. Show this video to build background knowledge and connect the lesson s activities to the role of a PT. (3:33). In order to connect the activities to the career of PT, show this short video as part of the opening. Otherwise, the activities may seem disjointed. Work Time Biomechanics: An Exploration in Levers (20 min) Our bodies use a lot of levers to accomplish the work of movement. Physical therapists also use their knowledge of biomechanics, or the ways our bodies are like machines, to assess and treat people s injuries so that they can move more normally and experience less pain after they heal. Understanding how levers work and the types of levers that make up our bodies is very important information for the physical therapist. How is your arm a lever? 1. Did you know parts of our body function as simple machines? Project video that shows how to balance using one s arm as a lever: (1:25). Note the terms used in the left corner. 2. Model the activity. o Fill a bucket halfway with sand or a bag with books (determine the number based on size and weight of the books available in the classroom). o Place your arm flat on the table with your hand and approximately four inches below your wrist extending over the edge of the table, palm facing upwards. 4

5 o Invite a YP to hang the prepared bucket/bag across the palm of your hand. o Keeping your elbow on the table, lift the bucket up. o Ask: On a scale of 1-5, how much effort did it take to lift the buckets/bag? (1= no effort and 5= a lot of effort.) State your impression aloud. o Have the YPs record their data in the table. o Model filling the bucket with sand/adding books to bag. o Check for Understanding: I would repeat this experiment with the new weight, keeping my elbow and arm in the same placement. I am only changing one variable. What variable am I changing? 2. Model extending the effort arm by using a yardstick, but do not repeat the experiment. 3. Invite the YP to read the <How Is Your Arm a Lever?> procedure in their packet. o As they read, distribute materials to partners. Lever Vocabulary Basics (5 min) 1. Distribute the <Lever Vocabulary>. o Tell the young professionals that a seesaw is a type of lever. You will use it as an example to use the vocabulary in context, and everyone should label the image on their page as they follow along. o Distribute one sticky note (labeled fulcrum, effort, load, and resistant point) to each group. 3. Project the seesaw image from the <Lever Vocabulary> handout. 4. Invite groups to discuss where they would place their label. Allow time to discuss, then use equity sticks to call on representatives from each group to bring their label and place it on the projection. 5. After all groups have added their labels, ask if anyone has any suggested changes to the label placements. o The lever and the base is the fulcrum. o The effort would be the child lifted into the air. o The load is the child on the ground. o Resistance force, in this case, is gravity. o The mechanical advantage is what allows a child to lift the weight of another child even a child who is much bigger, or an adult! 5

6 2. Check for understanding: Think back to your arm in the lifting activity. What was the fulcrum? The load? The effort? Now that we have a better understanding of how levers work, we can use this information to figure out the type of lever the arm is. With this understanding, we can assess and rehabilitate the broken arm injury sustained by the young skateboard accident patient. Muscle Density Activity (20 min) As an extension, turn this into a mathrich activity by challenging students to convert between units of measurement. Understanding how our bones and joints act as levers allows us to use biomechanics to rehabilitate the body. As Physical Therapists, we must also understand how the muscles in our body function as simple machines that will work together with the bones during the process of recovery. 1. Explain to students that our muscle fibers, or the material that makes up the muscles, are configured to act as levers and pulleys, but are actually more similar to rubber bands. 2. Ask a student volunteer to pass out the materials for the activity (rubber bands and rulers). 3. Tell the YPs that they will be measuring with a ruler how far they can stretch a single rubber band without breaking it, using their thumbs and forefingers. 4. Group students in pairs. One will stretch the rubber band while the other measures the distance in centimeters. Have the partners switch roles and repeat. Each YP should record their distance on their <Muscle Density Data Table>. 5. Next, students will explore if an increase in muscle density (number of bands) or size (width of the band) will make the rubber bands get stronger, or more difficult to stretch. o Have the YPs repeat the procedure above with two, three, four, etc. bands on their thumbs and forefingers. o Ask: What conclusions can you draw from your data? Was it harder or easier to stretch the rubber bands as you increased the number of bands? o YPs should repeat the procedure with wider rubber bands on their thumbs and forefingers. o Ask: What conclusions can you draw from your data? Was it harder or easier to stretch the rubber bands as you increased the width of the band? 6. Have the pairs work together to answer the <Muscle Density Debrief Questions>. 7. Circulate and assist groups as necessary. It is very important to record the distribution of bands before the activity and again at the end of class. Make certain students know you have a list of who has the bands and who has returned them as facilitator you are responsible for ensuring all bands are returned. Any safety violation results in sitting out. This is an important tone to set, and important to enforce calmly and consistently. Emphasize the reasoning instead of the answer. Instead of confirming ( that s right! ), ask for justification and reasoning: What evidence from the data supports your conclusion? 6

7 8. Ask: How are rubber bands a model of muscle fibers? How was strength being measured/modeled? 9. Use equity sticks to solicit responses from the group. 10. Listen for: The rubber bands represented muscle fibers. As the muscle fibers increased in density (more bands) and size (wider bands), they became stronger, or harder to stretch. Understanding the strength and limitations of our muscle fibers is very important for the process of rehabilitation. As Physical Therapists, it allows us to determine the best exercises for the skateboard accident patient to perform based on his ability to use and stretch his weakened muscles with his sustained injuries. Our knowledge of biomechanics has allowed us to come up with a list of rehabilitating movements and exercises for the patient that will bring him closer to recovery and full mobility. Closure (5 min) Careers in Biomechanics Today, we learned that Physical Therapists rely on the principles of biomechanics to help their patients recover from injuries. However, many other careers require the use and application of biomechanics. Can you think of other careers that rely on biomechanics? 1. Provide think time for the YPs. 2. Encourage paired thinking and sharing of ideas. 3. Use equity sticks to solicit responses. 4. Ask: What careers did you come up with? 5. Listen for: Athletes, Athletics Coaches, Athletic Trainers, Community Recreation Instructor, Orthopedic Surgeon, Biomechanics Researcher. The point of this brief closure is to get students to transfer their new knowledge of biomechanics to the real world. Where else would this knowledge be useful outside of a hospital? 7

8 Name: Date: PHYSICAL THERAPY: How Is the Body Like a Machine? Today s Learning Objectives: I can: Explain how the muscles and bones of the human body function together as levers. Justify categorization of lever types. Biomechanics is the application of the principles of mechanics (physics) to the living body. The body s skeletomuscular system is comprised of levers that give it mechanical advantage when working with the force of gravity to produce movement. Physical therapists understand these principles and use them to rehabilitate injuries so that people can experience normal range of motion in their joints and movement that is not compromised. In this lesson, I will explore the action of levers and how the body is made up of many levers. Today s Activities: Emergency Scenario: Rehabilitation Biomechanics: An Exploration in Levers Card Sort Protocol Careers in Biomechanics 8

Emergency Scenario: Rehabilitation After any trauma to the body, rehabilitation of the injured areas is usually required as an important part of treatment.

9 Emergency Scenario: Rehabilitation After any trauma to the body, rehabilitation of the injured areas is usually required as an important part of treatment. As a physical therapist in the hospital, you see a variety of injuries and problems that arise with the skeletal-muscular systems as a result of disease. Your latest patient, an adolescent boy with a brain contusion and a broken arm, has been assigned to your caseload. In analyzing his case, you will focus on physical therapy exercises to regain movement and strength in his broken forearm. Since you were in middle school, science was your favorite subject, especially physical science. In high school, you discovered that physics can be applied to the human body in an area of study called biomechanics. What you really love about your career is that you can apply what you know about physics to the human body in order to help people feel better. 9

How Is Your Arm a Lever? Procedure (adapted from http://www.education.com/scienc e-fair/article/human-machine/) 1. For this activity, you can use either a bucket of sand or a bag filled with books. 2.

10 How Is Your Arm a Lever? Procedure (adapted from e-fair/article/human-machine/) 1. For this activity, you can use either a bucket of sand or a bag filled with books. 2. Fill the bucket halfway with sand or the bag with books provided by your teacher. 3. Place your arm flat on the table. Your hand and about four inches below your wrist should extend over the table s edge. The inside of your elbow should be facing upward. 4. Have your friend hang the bucket/bag across the palm of your hand. 5. Keeping your elbow on the table, lift the bucket up. 6. Repeat, this time with the bucket full of sand/with double the books. 7. On a scale of 1-5, how much effort did it take to lift the buckets? (1= no effort and 5= a lot of effort.) Record your answer in the data table. 8. Remove sand/books until the bucket is again halfway filled. 9. Put the handle of the bucket around a yardstick. 10. Set your arm on the table as before, but hold the yardstick with the bucket hanging off it. The bucket/bag should be 2-3 feet farther from the edge of the table. 11. Lift the bucket again. 12. On a scale of 1-5, how much effort did it take to lift the bucket/bag this time? (1= no effort and 5= a lot of effort.) Record your answer in the data table. 13. Slide the bucket/bag to different places on the long stick and note the different amounts of effort. Arm Only: Bucket ½ Full Arm Only: Bucket Full Stick Extension: Bucket ½ Full Stick Extension: Bucket Full Participant 1 Participant 2 10

11 14. Use your data table to help you answer the following questions: How does the effort to lift the bucket on the long stick compare to the effort of moving it when it was in your hand? Does it feel like the bucket contains more or less sand than the first trial? Explain your reasoning. 11

12 Lever Vocabulary Vocabulary Word Prediction of Meaning Definition (and picture) Lever Fulcrum Effort Load Resistance Force Mechanical Advantage 12

13 Biomechanics Challenge Question Bones and Muscles as Levers (adapted from the Haspi curriculum) The study of biomechanics applies concepts of physics to the movement of the body. While the biomechanical movement of the human body is complex, there are also some simple machines at work. The movement of the body results from the interaction between bones, muscles, and joints. Many of these interactions form a simple biological machine known as a lever. Within the human body, bones are considered the lever arm; the axis of a joint is the fulcrum; resistance is created by the weight of the body part or object being moved or pushed upon; and muscles are considered the effort since they create the actual motion. What class of lever is at work when you raise a glass of water from a table to your mouth? Diagram and label the sources of the fulcrum, resistance (or load), and effort. Class of Lever: Diagram (with labels): What class of lever is at work when you lift a barbell over your head? Explain the sources of the fulcrum, resistance (or load), and effort. 13

14 Muscle Density Data Table Directions. Measure the distance you can stretch your rubber band(s) in centimeters and record in the table below. Group member Partner A Single Band Two Bands Three Bands Four Bands Five Bands Six Bands Seven Bands Mediumwidth Band Largewidth Band Partner B 1. What conclusions can you draw from your data? Was it harder or easier to stretch the rubber bands as you increased the number of bands? 2. Was it harder or easier to stretch the rubber bands as you increased the width of the band? Justify your answer with evidence from the data. 14

Muscle Density Debrief Questions Directions. Answer the questions below in complete sentences. When possible, justify your answers using evidence from your data table. 1.

15 Muscle Density Debrief Questions Directions. Answer the questions below in complete sentences. When possible, justify your answers using evidence from your data table. 1. How are rubber bands a model of muscle fibers? 2. How was strength being measured/modeled in this activity? 3. Do our muscles have limitations? What evidence from the activity can you use to support your answer? 15

16 Facilitation Documents: 16

17 Lever Vocabulary Vocabulary Word Prediction of Meaning Definition (and picture) Lever A solid beam or rod that rests or pivots on a fulcrum. Fulcrum The point on which a lever rests, is supported, or on which it pivots. Effort The applied force a person puts into the lever. Load The weight or mass that is supported by the lever. Resistance Force The force that must be overcome to do the work. Mechanical Advantage The number of times a machine multiplies the effort (applied force). 17

18 Biomechanics Challenge Question (for teacher reference) Bones and Muscles as Levers (adapted from the Haspi curriculum) The study of biomechanics applies concepts of physics to the movement of the body. While the biomechanical movement of the human body is complex, there are also some simple machines at work. The movement of the body results from the interaction between bones, muscles, and joints. Many of these interactions form a simple biological machine known as a lever. Within the human body, bones are considered the lever arm; the axis of a joint is the fulcrum; resistance is created by the weight of the body part or object being moved or pushed upon; and muscles are considered the effort since they create the actual motion. What class of lever is at work when you raise a glass of water from a table to your mouth? Diagram and label the sources of the fulcrum, resistance (or load), and effort. Raising a glass of water from a table to your mouth is done with a class 1 lever. The forearm acts as the lever arm, the elbow joint is the fulcrum, the resistance is the forearm and glass of water, and the effort is created by the bicep muscle. What class of lever is at work when you lift a barbell over your head? Explain the sources of the fulcrum, resistance (or load), and effort. Lifting a barbell over your head is done with a class 3 lever. The humerus bone, radius, and ulna (the arm bones) are the fulcrum. The resistance is the arm and the weight. The effort is created by the trapezius and deltoid muscles (chest and back muscles). 18

Students will: Explain how the muscles and bones of the human body function together as levers. Justify categorization of lever types.

PHYSICAL THERAPY Essential Question: How Is the Body Like a M achine? Learning Targets: Students will: Explain how the muscles and bones of the human body function together as levers. Justify categorization