Chlorophyll Chromatography

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Science of NHL Hockey: Reflexes & Reaction Time
Subject Area: Life Science
Grade Level: 5–8 (Life Science)
Lesson Title: Reflexes & Reaction Time
National Science Education Standards
 Science as Inquiry: 5–8
 Regulation and Behavior: 5–8
Suggested Prior Knowledge: function of muscular and nervous systems, central nervous
system, location of sensory and motor neurons, definition of stimulus, use of stopwatch.
Purpose and Introduction: Although all hockey players (and other athletes) rely heavily on
reflexes and quick reaction times, this video focuses on the quickness with which the goaltender
must react to stop the offensive shots. The activity enables students to differentiate between
reflexes (reactions that do not involve the brain) and other stimulus-reaction responses (those
that do involve the brain) and develop understanding of how reaction times can differ.
Key Vocabulary:
impulse—electrical signal that travels along neurons.
reaction time—period of time between the presentation of the stimulus and the ensuing
reaction.
receptor—end of sensory neurons.
reflex arc—shortcut through the spinal cord traveled by an impulse.
reflex—unconscious muscle response to a stimulus that does not involve the brain.
sensory afferent pathway—chain of nerve structures that transmit the nerve impulse.
stimulus-reaction response—the result of a nerve impulse, triggered by a stimulus,
traveling through sensory nerves to the brain and back through motor nerves.
Objectives:
1. Students will differentiate between a reflex and other stimulus-reaction responses.
2. Students will design and carry out an investigation to test reflex reaction time.
3. Students will make generalizations about reaction times involving reflexes and other
stimulus-response reactions.
Materials:
- computer access
- ruler or meter stick
- various materials depending on student designs
Reflexes and Reaction Time (Middle School)
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Procedure:
1. Before or after students view the video, have them brainstorm a list of actions that are
reflexes or that require quick reaction times. Elicit from volunteers the sensory afferent
pathway that an impulse follows in each action. Help students differentiate between true
reflexes and other stimulus-response actions by identifying which are more likely protective
actions that could occur in many situations and which might be practiced or associated with a
particular sport or activity. Share with students primitive reflexes observed in infants, such as
the sucking, Moro, and grasping reflexes that enable the survival of infants. (See Additional
Resources below.)
2. Discuss with students how reaction time differs between a true reflex and a reaction that
requires, at least initially, some level of conscious thought. Questions such as the following
will help stimulate discussion:
 How do nerves cause muscles to effect actions?
 What is a reflex? How does it differ from other responses?
 Does everyone have the same reflexes? What are some examples?
 How does the need for an impulse to travel through the brain impact reaction time?
 Can reaction times be improved with practice?
 Can true reflex reaction times be improved with practice?
 Can you stop reflexes from occurring? Can you stop other kinds of reactions?
3. Lab protocols should be followed, incorporating safety equipment. Goggles must be worn at
all times.
4. Ask students to think of ways to differentiate among the different kinds of actions they
discussed earlier. Guide them to see how some actions happen automatically, without
thinking or without practice. Divide students into small groups and challenge them to test for
reflexes that remain after infancy, such as the blinking, patellar, startle, and pupil constriction
reflexes. Students can research these reflexes and devise safe ways to test for each one. If
needed, prompt student thinking with ideas such as the following:
 The tester and a respondent might stand on opposite sides of a strong window. The tester
then throws cotton balls at the respondent’s face.
 A respondent might sit in a chair with his or her legs crossed, but looking away from the
tester. A tester (of the same gender) could use the side of his or her hand to lightly tap
just below the patella, or kneecap, of the respondent.
 A tester could engage a group of respondents in an activity, such as listening to music,
reading, or watching a show. The tester then, at a random time, slams a book on a desk to
make a loud noise. The respondents then record their reactions to the noise. And they
could discuss how their responses can change based on what they are now expecting
[similar to a goalie…]
 In a darkened room, a tester could use a stopwatch to time how quickly a respondent’s
pupil constricts to maximum level once the bright, overhead lights have been switched
on.
5. Encourage students to develop questions that emerge from a desire to better understand
reflexes. They could determine how reaction time might be measured, such as timing and
Reflexes and Reaction Time (Middle School)
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degree of stimulus. For example, students might throw different sized balls, such as cotton
balls, table-tennis balls, foam balls, and inflatable beach balls, or the loudness of the sound
used to trigger the startle reflex could be varied. Encourage students to allow respondents to
undergo several trials of the tests to determine the effects of practice and anticipation on
reaction time.
6. Then instruct students to research ways to test reaction time for an action that requires, at
least initially, some degree of intention. Many students may be familiar with the classic
“ruler drop.” In this activity, one individual suspends a ruler or meter stick in the air, with the
0 mark at the bottom. A second individual holds his or her thumb and forefinger positioned
slightly apart at the 0 mark. The first individual drops the ruler without warning, and the
second individual grasps the ruler as quickly as possible between the thumb and forefinger.
Some advantages of this method are the readily available equipment and that measurements
on the ruler can be equated with time based on the following chart. Many reaction time tests
also are available online for students to use. (See Additional Resources.) Instruct students to
again allow respondents to undergo several trials to determine the effects of practice and
anticipation on reaction time in these kinds of tests.
Distance (centimeters)
5
10
15
20
25
30
Time (seconds)
0.10
0.14
0.17
0.20
0.23
0.25
7. Have students draw conclusions about whether those respondents with faster or more
sensitive reflexes also have faster reaction times in other kinds of activities. Students might
make comparisons of the observed reaction times with that of goalie Pekka Rinne. Remind
students that the video explains that the quicker the reaction time, the more like a reflex the
action is. Guide them to understand that quicker or more sensitive reflexes may or may not
result in faster reaction times, but generally practice does.
8. As an extension, suggest the tests be administered under different distracting conditions, such
as loud music, intermittent cheering from “fans,” while carrying on a conversation, while
reading and responding to a text message, and so on. Encourage students to draw conclusions
about how distractions such as these impact reaction time of reflexes and other kinds of
stimulus-response actions and what they might do to mitigate those effects during certain
activities.
Additional Resources:


http://www.exploratorium.edu/hockey/save1.html
http://biology.clemson.edu/bpc/bp/Lab/110/reaction.htm
Reflexes and Reaction Time (Middle School)
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







http://www.yalemedicalgroup.org/stw/Page.asp?PageID=STW001803
http://sciencenetlinks.com/lessons/reaction-time-1-how-fast-are-you/
http://articles.baltimoresun.com/1999-09-30/sports/9909300145_1_severna-parkgoalie-scoring-circle
http://www.nlm.nih.gov/medlineplus/ency/article/003292.htm
http://www.healthofchildren.com/N-O/Neonatal-Reflexes.html
http://www.exploratorium.edu/baseball/reactiontime.html
http://www.topendsports.com/testing/reactiontest.htm
http://www.bbc.co.uk/science/humanbody/sleep/sheep/reaction_version5.swf
Reflexes and Reaction Time (Middle School)
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Student Worksheet for Reflexes & Reaction Time
Experiment Title: _____________________________Date: __________Name: _____________
Student Question or Hypothesis:
____________________________________________________________________________
Materials:
- computer access
- ruler or meter stick
- various materials depending on student designs
Safety Concerns:
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Procedure: ____________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
Reflexes and Reaction Time (Middle School)
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Data:
Observations: __________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Analysis of Data:
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
Conclusion: ___________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
Reflexes and Reaction Time (Middle School)
6
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