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Muscles In MotionMuscles-In-Motion

  • Subject:
  • |
  • Grade(s): 6-8
  • |
  • Duration: One class period

Lesson Plan Sections

Objectives


Students will understand the following:
1. Different muscles are used to perform different body motions.
2. Muscles in the upper arm called biceps are used to flex the arm.
3. Muscles in the upper arm called triceps are used to extend the arm.

Materials


The following materials should be distributed to each group:
• Five- or six-pound dumbbell

Procedures


1. Ask your students to flex their arms by bending their lower arms up from the elbow. Then have them extend their arms by raising their arms straight above their heads. Make sure students understand the terms flex and extend .
2. Ask your students if they know which muscles they used to perform each action. If they are unfamiliar with the terms biceps (flex) and triceps (extend), introduce the terms now.
3. Ask your students to vote on whether the following statement is true: Most people's biceps are stronger than their triceps.
4. Tell students they are going to perform an experiment that will test the statement.
5. Divide the class into groups, giving each a dumbbell to work with.
6. Instruct group members to take turns doing the following exercise: Standing with your back against a wall, hold the dumbbell in your dominant hand, letting the dumbbell hang at your side with your arm fully extended downward. Raise the dumbbell by bending your arm from the elbow toward your face as far as you can. Lower the dumbbell by fully extending the arm downward.
7. Have each student repeat the exercise until she or he feels tired. Group members should record the number of repetitions for each student.
8. Next, have students take turns doing the following: Standing with your back against a wall, hold the dumbbell in your dominant hand, letting the dumbbell hang at your side with your arm fully extended downward. Bend your arm at the elbow, bringing the dumbbell up toward your face and holding the dumbbell next to your ear on the same side of the body. Rotate your wrist so your palm is facing away from you. Now push the dumbbell straight up into the air until the arm is fully extended; then return the dumbbell so that it is next to your ear again.
9. Have each student repeat the exercise until she or he feels tired. Group members should record the number of repetitions for each student.
10. Compute class averages for the "flex" and "extend" exercises.
11. Discuss whether the results of the test agreed with the class vote prior to the experiment.
12. Continue the discussion by asking students what makes one muscle stronger than another.
13. Have each student describe the experiment in a written paragraph, accompanied by a graph representing the results for his or her group.

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Adaptations


Adaptations for Older Students:
Have students draw diagrams, based on research, of the muscles of the human arm, labeling biceps and triceps. They might also explain, in writing, the chemical changes that occur in a muscle when it contracts and when it becomes fatigued.

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Discussion Questions


1. What makes a person disabled? Is it the limitations of the person or the artificial barriers created in our environment?
2. Will machines ever be built that can move and react just like a person? Should they be built?
3. For what purposes could people use a computer that simulates human movement? Categorize as positive or negative uses.

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Evaluation


You can evaluate your students on their paragraphs and graphs using the following three-point rubric:
Three points: paragraph provides clear, accurate, and complete description of experiment; graph clearly labeled and easily interpreted
 
Two points: paragraph provides adequate description of experiment; graph unclear
 
One point: paragraph vague and sketchy; graph unclear
 
You can ask your students to contribute to the assessment rubric by determining what information should be included in the paragraph and how the graph should be set up.

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Extensions


Muscle Models
Have your students make models of their arm muscles. Give each group or pair of students two cardboard strips, 2 inches by 6 inches; two paper fasteners; tape; a hole puncher; a red balloon; and a blue balloon. Then have them follow these instructions:
  1. Punch a hole in each cardboard strip, about 1.5 inches from the end, and in both ends of each balloon.
  2. Tape the two strips together end to end so that the holes are about 3 inches apart. The strips will bend like a joint on the taped side. (One strip represents the upper arm; the other represents the lower arm; the joint represents the elbow.)
  3. With a paper fastener, attach the two balloons to opposite sides of the "upper arm," with the red balloon on the taped side. Attach the other end of each balloon to the "lower arm" in the same way.
  4. Bend the "arm" at the "elbow," noticing what happens to the balloons. The red balloon will become shorter, or "contract," while the blue one will stretch out, or "relax."
Explain that the red balloon is like the biceps muscle and the blue balloon is like the triceps. One relaxes as the other contracts.

Human Movement Career Fair
Scientists and engineers study movement, developing devices to improve conditions for injured people, developing machines that move like humans, and developing computer animations that move like humans. Put on a Human Movement Career Fair. Invite your students to investigate careers involved in human movement. Each student can explore one of those careers and create a science-fair-type display board on that career. After students present their displays, discuss with the class the similarities and differences between the various careers in terms of education required, working environment, specific activities, people contact, and so on. Encourage students to evaluate their own interests and which careers they might like or not like.

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Suggested Readings


The Human Machine
R. McNeill Alexander, Columbia University Press, 1992
Why can robots never replicate all human motions exactly? "The Human Machine," with its explanations of the mechanical principles underlying the full range of human movement, explains the uniqueness and complexities of our locomotion.

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Links


Realistic Animation of Legged Running on Rough Terrain
Here is an abstract for students wanting a deeper understanding of the physical variables behind the design of walking robots.

On The Run
Take your students up to the next step of Computer Assisted Drawing--"CAD"--with the 3-D robotic design animations found at this site.
 

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Vocabulary


Click on any of the vocabulary words below to hear them pronounced and used in a sentence.
speaker    tendon
Definition: A tough cord or band of dense white fibrous connective tissue that unites a muscle with some other part (as a bone) and transmits the force which the muscle exerts.
Context: Humans and other animals store and recover energy in tendons and muscles and, with each step, bounce on the ground like a rubber ball.
speaker    rehabilitate
Definition: To restore or bring to a condition of health or useful and constructive activity.
Context: I developed several specialized artificial limbs that eventually rehabilitated me as a climber.
speaker    ligament
Definition: A tough band of tissue connecting the articular extremities of bones or supporting an organ in place.
Context: In the biological leg there are tendons, there are ligaments, there are all these structures that act like springs so when you step off a curb, all those tendons and whatnot stretch.
speaker    biomechanics
Definition: The mechanics of biological and especially muscular activity (as in locomotion or exercise).
Context: It is absolutely essential to have a minimal base knowledge in biomechanics because you are going to run into situations where evaluation of technique is not simply saying that the arms didn't go fast enough but you'll have to look at why they didn't go fast enough.
speaker    inertia
Definition: A property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force.
Context: Rigid bodies cannot stably rotate about their intermediate principle axis of inertia.

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Standards


This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.
 
Grade level: 6-8
Subject area: life science
Standard:
Knows about the diversity and unity that characterize life.
Benchmarks:
Knows that although different species look very different, the unity among organisms becomes apparent from an analysis of internal structures, observations of the similarity of their chemical processes and the evidence of common ancestry.

Grade level: 6-8
Subject area: technology
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Knows that there is no fixed procedure called "the scientific method," but that investigations involve carefully collected, relevant evidence, logical reasoning, and some imagination in developing hypotheses and explanations.

Grade level: 6-8
Subject area: technology
Standard:
Understands the interactions of science, technology and society.
Benchmarks:
Knows that science helps drive technology, providing knowledge for better understanding, instruments, and techniques.

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Credit


Jeffrey Leaf, technology teacher, Thomas Jefferson High School for Science and Technology, Alexandria, Virginia.

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