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22 Muscles and Movement
BROWARD COUNTY ELEMENTARY SCIENCE BENCHMARK PLAN
Grade 4—Quarter 3
Activity 22
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The student knows that the human body is made of systems with structures and functions
that are related.
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The student knows that to work collaboratively, all team members should be free to reach,
explain, and justify their own individual conclusions.
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The student knows that a model of something is different from the real thing, but can be
used to learn something about the real thing.
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ACTIVITY ASSESSMENT OPPORTUNITIES
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The following suggestions are intended to help identify major concepts covered in the activity
that may need extra reinforcement. The goal is to provide opportunities to assess student
progress without creating the need for a separate, formal assessment session (or activity) for
each of the 40 hands-on activities at this grade level.
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1. Point out that, in this activity, students made a model to study how something in their
body works. Models are good because they help us visualize how things work. But,
sometimes they are not accurate. Have students make a list with two columns: label one
column “accurate,” the other “inaccurate.” In the “accurate” column, students should
write ways they think the model was good and helpful and accurately showed how arm
muscles work. (The model helps show how flexor and extensor muscles work in
opposition as our arm moves.) In the “ inaccurate” column, have students list ways the
model might be misleading. (Our bones are not hollow; muscles are not thin bands;
muscles are made up of specialized cells, not rubber; there are two bones in the lower
arm, not one; and so on.)
2. Use the Activity Sheet(s) to assess student understanding of the major concepts in the
activity.
In addition to the above assessment suggestions, the questions in bold and tasks that
students perform throughout the activity provide opportunities to identify areas that may
require additional review before proceeding further with the activity.
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activity 22 Muscles and Movement
© Delta Education. Photocopying and distribution prohibited.
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22 Muscles and Movement
OBJECTIVES
PREPARATION
1
Students observe how muscles contract to
make the body move.
The students
construct a model of the arm
observe how muscles move bones
SCHEDULE
About 45 minutes
VOCABULARY
biceps
extensor
flexor
muscle
muscular system
tendon
triceps
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MATERIALS
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For each student
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Activity Sheet 22
1 pair safety goggles*
For each team of two
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2
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ball, table tennis
paper clips
pushpin
rubber bands, thin
ruler, metric
tubes, cardboard, large
For the class
1 btl glue
1 roll tape, masking
*provided by the teacher
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Make a copy of Activity Sheet 22 for each
student.
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Each group of two students will need one
tube with a ball glued to the end of it, one
plain tube, two paper clips, two thin
rubber bands, one pushpin, one metric
ruler, and several pieces of masking tape.
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You will need to glue the table tennis balls
to the cardboard tubes at least 24 hours
before conducting this activity. Obtain
from the kit the container of glue and one
tube and one table tennis ball for each
team of two students. Place a small
amount of glue around the rim at one end
of each tube and set a ball on that end.
The glue must be completely dry before
the students conduct the activity.
BACKGROUND INFORMATION
Muscles are body tissues that are able to
contract. There are three kinds of muscles in
the human body: skeletal, smooth (found in
some internal organs), and cardiac (found in
the heart). This activity focuses on skeletal
muscle.
Skeletal muscle is striated, which means that
alternating light and dark stripes can be seen
when the muscle tissue is viewed under a
microscope. We move skeletal muscles
voluntarily, that is, these muscles are under
our conscious control.
Almost all skeletal muscles (with the
exception of the tongue and the pharynx) are
attached to bones by tendons. When skeletal
muscles contract, they move the bones to
which they are attached. A muscle that causes
a body part to bend when it contracts is called
a flexor. A muscle that causes a body part to
extend or straighten out when it contracts is
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called an extensor. Flexor muscles and
extensor muscles work together to make our
bodies move.
Activity Sheet 22
Muscles and Movement
1. Label the contracted and relaxed muscles.
In this activity, students will build a model of
a human arm including the forearm and upper
arm. By bending the model arm at the elbow
and then straightening it out again, they will
be able to observe the action of the biceps (a
flexor muscle on the front of the upper arm)
and the triceps (an extensor muscle on the
back of the upper arm).
contracted
relaxed
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2. Draw your model of the arm. Use the following labels: elbow, wrist,
shoulder, extensor muscle, flexor muscle, biceps, and triceps.
Drawings should be similar to Figure 22-2.
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Write the word muscle on the board. Tell
students that muscle is body tissue that
functions in movement. Remind students that
bones support our bodies and protect vital
organs. Then ask, What do muscles do?
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Write the words muscular system on the
board. Tell students that movement in our
bodies is the responsibility of the muscular
system. The muscular system is made up of
all the muscles in the body including muscles
that move our limbs and heart.
Additional Information
Students’ answers may include that muscles
allow us to move our bodies and to lift, push,
and pull things.
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Tell students to feel their arm muscles as they
bend and swing their arms. Ask, What do you
think is happening to cause your arm to
move?
Tell students to watch the big muscle on the
front of their upper arm as they hold their
arm out straight, palm-up, and then bend it at
the elbow.
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activity 22 Muscles and Movement
Students will probably say that their muscles
are allowing them to move their arms.
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Guiding the Activity
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Guiding the Activity
Additional Information
Yes. It got shorter.
Ask, Did the shape of your upper arm
muscle change? Did it get shorter or
longer?
Tell students that when a muscle contracts, it
gets shorter (see Figure 22-1).
contracted
contracted
Write the word tendon on the board. Tell
students the tendons are the tissues that
connect muscle to bone.
relaxed
relaxed
Distribute Activity Sheet 22 and have the
students complete question 1.
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Write the terms flexor and extensor on the
board. Inform the students that a flexor is a
muscle that bends a body part. An extensor is
a muscle that straightens out a body part.
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Tell students to place one arm straight out in
front of them, palm-up, on their desk. Ask, If
you wanted to bend your arm at the elbow
and lift your forearm and hand off the desk,
would you use a flexor or an extensor
muscle?
Now ask, If you wanted to straighten out
your bent arm, would you use a flexor or
an extensor muscle?
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Figure 22-1. Muscle tissue, contracted and relaxed.
A flexor muscle would be used to bend the arm.
An extensor muscle would be used to
straighten the arm.
Tell students that they will construct a model
of an arm (both the forearm and upper arm)
from the step-by-step instructions you are
about to give them. Distribute the needed
materials to each team. Throughout the
assembly phase, offer help as needed.
Tell the teams to pick up the tube that has a
ball glued to one end of it and use a pushpin
to poke a hole in the tube 5 cm from the
other end. Tell them to poke another hole
directly opposite the first. Have them repeat
this procedure with the tube that does not
have a ball attached to it.
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Guiding the Activity
Additional Information
Next, tell them to straighten out a paper clip
and push it through the two pin holes in the
tube with the ball glued to it. With an equal
length of paper clip protruding from each
side of the tube, have them bend the ends of
the paper clip toward the open end of the
tube. Tell them to do the same to the other
tube by pushing the straightened paper clip
through the pin holes in the tube and
bending the ends of the clip toward the short
end of the tube.
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shoulder
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biceps
flexor muscle
triceps
extensor muscle
wrist
elbow
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Safety Note: Tell students to use caution
when handling the rubber bands.
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When all of the teams have finished
assembling, have them label their model (see
Figure 22-2). Tell them to write elbow at the
end of each tube closest to the ball, wrist at
the open end of one tube, and shoulder at
the open end of the other.
Figure 22-2. A model of the arm.
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It may be easier if one student holds the
tubes together while his or her teammate
extends the rubber bands and tapes the ends
of the paper clips in place.
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Using that same tube, instruct them to loop a
separate rubber band over each bent end of
the paper clip and tape the ends of the paper
clip against the tube. Then have them place
the tubes together so that the ball is in the
middle and the paper clips are at opposite
ends of the tubes. Tell them to carefully pull
the rubber bands over the bent ends of the
paper clip on the other tube and to tape the
ends of that clip against the tube.
Guiding the Activity
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Additional Information
Next, have one student in each team hold the
two tubes in a straight line while the other
tapes the rubber band on one side of the
tube near the elbow end of the “forearm”
(wrist-to-elbow) tube.
On the other side of the apparatus, have
them separate the rubber band slightly and
tape it to the ball.
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Have students bend the model arm to
simulate what happens to the muscles of the
arm when the arm bends at the elbow.
Ask, Which rubber band represents the
flexor muscle?
Ask, When you bend the model arm, does
the flexor get shorter or longer? Why?
What kind of muscle is represented by the
other rubber band?
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an extensor muscle
It is longer because it is relaxed. Contracting
(shortening) the extensor muscle would
cause the bent arm to straighten.
Write the words biceps and triceps on the
board. Tell students that the biceps is on the
front and inside of the upper arm, and the
triceps is on the back and outside of the
upper arm. Begin a discussion by asking,
Do you think your biceps is a flexor or an
extensor muscle?
The biceps bends the arm. Therefore, it is a
flexor muscle.
Ask, Do you think your triceps is a flexor or
an extensor muscle?
The triceps extends or straightens the arm.
Therefore, it is an extensor muscle.
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It gets shorter because it is contracting.
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Is it longer or shorter when the model arm
is bent? Why?
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Students should identify the section of rubber
band that extends from “shoulder” to
“elbow” on the inside of the model arm as
the flexor muscle.
Have students identify the “biceps rubber
band” and the “triceps rubber band” on their
model. Then write the word tendon on the
board. Tell students that muscles are
attached to bones by tendons. Ask, Which
part of your model represents the tendons?
Students should respond that the paper clips
and tape represent tendons since they attach
the rubber bands (muscles) to the cardboard
tubes (bones).
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Guiding the Activity
Additional Information
Have students complete question 2 on their
activity sheets.
A good place to look for muscle-tendon-bone
interaction in the human body is the
calf/Achilles tendon/heel area. Have students
feel their own Achilles tendon. Tell them that
they also have tendons in their elbows.
Tell students to place their fingertips on their
cheeks just in front of their ears. Tell them to
clench and unclench their teeth. They will feel
their jaw muscles contracting and relaxing.
CLEANUP
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activity 22 Muscles and Movement
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SCIENCE JOURNALS
Have students place their completed activity
sheets in their science journals.
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The arm models may be disassembled. The
rubber bands and tubes, half of which have
a table tennis ball attached, may be
returned to the kit. The paper clips and
pieces of tape should be discarded.
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REINFORCEMENT
Connections
Science Challenge
Science and Careers
Have interested students research the
smooth muscle of the human body. Their
research should reveal answers to several
questions: Is smooth muscle under our
conscious control? What organs are made of
or contain smooth muscle? What are the
functions of these organs?
Invite a physical therapist to visit the class to
discuss the education and training required
for such a career. Ask the visitor to describe
various common disorders and injuries for
which physical therapy is helpful and to
explain the therapy process. If possible,
arrange small-group field trips to a therapy
center so the students can observe the
therapy process.
Science Extension
Have students do the following activity to
discover what happens when muscles are
overworked: Count how many times you can
rapidly open and close a spring clothespin in
30 seconds, and record the results. (Each
opening and closing should be counted as
one action.) Without resting between trials,
repeat the test four more times, and record
the results for each trial.
Science and Health
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In a follow-up discussion, have students
compare their results. What happened as
trials were repeated? (Muscles began to tire,
and the number of actions decreased.) Help
students make a bar graph of class results,
with the horizontal axis labeled Trial Number
and the vertical axis labeled Number of
Actions. Each bar will show the minimum and
maximum number of actions for each trial.
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Have students research why stretching and
warm-up exercises are important before more
strenuous exercise or physical activity. (If
muscles and tendons are exercised
strenuously when they are tight, injury is
more likely to occur.)
Science and the Arts
Ask students to investigate the major types of
joints in the human body and to identify
specific examples of each type. Have
volunteers use pictures cut from magazines
or their own drawings to prepare a bulletinboard display illustrating the joint types and
examples.
Science and Language Arts
The Achilles tendon is named after Achilles,
who, according to Greek mythology, was a
great warrior who fought in the Trojan war.
Encourage students to read the story of
Achilles in the book The Iliad to discover how
the Achilles tendon got its name.
Science, Technology, and Society
Encourage students to investigate devices
and technologies that have been
developed to aid people with orthopedic
handicaps.
As appropriate, encourage supervised use
of the Internet for research projects related
to the human body. A list of related
websites is provided in the References and
Resources section.
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activity 22 Muscles and Movement
© Delta Education. Photocopying and distribution prohibited.
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