STRIDES TO FREEDOM: HOUDINI’S STORY  

Drawing by Kim Haymans-Geisler

by  Ann Marie Froehle    (email ann.froehle@gte.net)  Max Geisler   (Max's Web Page)  (email Max Geisler) Philip Holley   (email Pbats@aol.com)  Erin Tiderman   (email Erin Tiderman)

 
 

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Summary/Abstract
 

This lab experiment was developed in conjunction with the Woodrow Wilson National Fellowship Foundation during the summer of 1998.  The developers participated in the Biology Leadership Institute, "Life in Motion."

Each research and development group had the same broad assignment: to develop and publish a web product, presenting a hands-on, inquiry based lab experience focusing upon the movement of living things.  Conformity to the National Science Education Standards, developed by the National Research Council, was strongly encouraged.

The research of our group focused upon the stride length and speed of a hamster named Houdini. Plotting his stride length against various speeds, we recorded a straight-line function, consistent with the research of McNeil Alexander (1985).

We are deeply indebted to the Biology Leadership Institute and its staff, and to Houdini the Hamster, whose cooperation and curiosity were invaluable.

Of course, we welcome your comments and suggestions at the email addresses above.

• To improve the observational and graphing skills of students
• To increase students' awareness of how living organisms move

• Secondary classes in comparative or human anatomy
• Secondary classes in general biology

• The time allocated for this lab should include at least 20 minutes for an introduction on stride, stride length, measuring speed, and the writings and equation of Alexander's formula relating stride length and speed.  If desired, the teacher may also include instruction on "dimensionless speed."
• Hamsters are nocturnal.  Our attempt during early daylight hours to measure the stride length and speed of Houdini resulted in one painful bite and four wary biology teachers.

• Butcher paper
• Hamster
• Paint
• Ruler
• Stop watch
• Graph paper

Stride length is defined as the distance between steps of the same foot of an organism. It may be measured from the back, center, or front of the footprint as long as consistency is maintained.

According to Alexander (1985), the stride length compared with speed for any organism is proportional to the size of the organism, plotting as a straight line. (For example, if a giraffe and a lizard are traveling at the same speed, then the giraffe will take fewer strides because its legs are much longer.) Species of different size and mass tend not to plot on the same line, although their individual lines tend to have similar slopes.

As a result of his research, Alexander also proposed a formula for "dimensionless speed."  This formula compensates for mass and volume differences between species, and allows the stride length of any specie to be  plotted against speed on a single linear function, with the exception of certain hopping bipeds and exoskeletal organisms. For these, he proposed alternative formulae.

www.wdn.com/mirkin/6170;
www.execpc.com/~blankda/goodfoote;
www.runnersworld.com/training/oastride;
www.seaworld.org/physics/inpark

The Student Lab
 

Investigation: 

How does the stride length of a hamster compare with that of larger animals?

Research:

Stride length is defined as the distance between steps of the same foot of an organism. It may be measured from the back, center, or front of the footprint as long as consistency is maintained.

According to Alexander (1985), the stride length compared with speed for any organism is proportional to the size of the organism, plotting as a straight line when the organism is observed at various speeds.  In addition, the lines for different organisms tend to be separate, since organisms of different size take more (or less) strides to maintain the same speed.

Consider a giraffe and a dog running at the same speed, for example. The giraffe will take fewer, longer strides at any given speed, because its legs are much longer.

Possible internet links for further studies:
www.wdn.com/mirkin/6170;
www.execpc.com/~blankda/goodfoote;
www.runnersworld.com/training/oastride;
www.seaworld.org/physics/inpark

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Hypothesis (Please fill in the blank):
If the stride length is plotted against speed for a hamster, then the stride length of the hamster should be

 ______________ than that of a dog (As measured by Alexander, 1985).
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Experimental Design:
1.  Obtain a hamster
2.  Measure at least 1 meter of butcher paper and set up a straight, narrow running path with borders to contain the
      hamster; label this as trial #1.
3.  Place the hamster at least 10 cm behind the starting line. Ink or paint the paper ahead of him/her so that he/she
        must run through it.
4.  Record the elapsed time from start to finish in Table #1.
5.  Move border so that clean butcher paper is exposed and label as trial #2.
6.  Repeat steps 3 and 4 to obtain at least 3 trials. Repaint feet as needed.
7.  If needed, use various stimuli such as food or sound to motivate the hamster to run.
8.  Record any notable hamster actions in the observation space; these may be important in analyzing data.
9.  Measure all of the stride lengths for each trial (see definition of stride length above), and record the average in Table.

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Observations:
 
   
 
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Data:  

  TABLE #1:  Time in seconds  

RUN #	TIME (SECONDS)
1
2
3
4
5
6
7
8
9
10
11
12

    TABLE #2:  AVERAGE STRIDE LENGTH (CM)  

RUN #	AVG. STRIDE LENGTH
1
2
3
4
5
6
7
8
9
10
11
12

 
Calculate the speed (m/sec) using the data from Table #1 and Table #2.
Hint:  Centimeters must be converted to meters!
   TABLE #3:  SPEED (M/SEC)  

RUN #	SPEED
1
2
3
4
5
6
7
8
9
10
11
12

 
 
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Graphing:   


Construct a graph using graph paper.  Plot Table #3 along the X-axis, and Table #2 along the Y-axis.  Make sure you plot run #1 stride length against run #1 speed.  Draw a line of best fit.  Title your graph and label your axes.
 

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Experimental Error:

In the following space report any sources of error that may have had an impact on your results.  If you could do this experiment over, what would you do differently?

 
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  Analysis and Conclusion:


Transfer the data from your graph onto the figure below.  Label line appropriately.
 
Comparative Speed and Stride Length

 

1.  How does your line of best-fit compare with the three other animals on the graph?

 
 

2. Do your results support the stated hypothesis? Explain your answer.
 
 
 
 

3.  What observations did you make that could have affected the results?
 
 
 
 

4.  If you were to find a 3-inch salamander, how would its stride to speed ratio compare to the other animals on the figure?  Show your answer by drawing an additional line on the graph.  Label line appropriately.
 
 
 
 

5.  How might the stride length of an ostrich be different from the other animals?  Design an experiment to determine how stride length compared to speed of an ostrich would fit on the figure in relation to the other animals. What factors would you need to consider? Write a paragraph explain your procedure and predict the outcome.  (hint:  think of legs)
 
 
 
 
 
 
 

6.  Is there a benefit of having a smaller stride length rather than a larger stride length? Or vice versa?  Explain.

 
 
 

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Extension/Reinforcement/Additional Ideas
 

While the Web Product Development Team chose to graph the motion of a hamster, other animals may certainly be investigated in a similar manner, either to verify the findings of Alexander or to search for exceptions. In addition, students may utilize the data collected in this process to challenge or confirm Alexander's formula for dimensionless speed. (Do other measured animals indeed plot on a single straight line?)

Of course, the writers are curious regarding creative uses and/or new ideas generated from this lab protocol. Contact via email is strongly encouraged if such ideas are generated by students or instructors.

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 Method of Evaluation/Assessment  
 

The authors have provided data charts and suggested questions associated with the hamster activity. These are intended as a basic evaluative instrument. Of course, students may prepare essays on the topic, or create reports and/or web products of their own. In addition, it is hoped that this exercise will generate many new questions and hypotheses that students may pursue on their own, and which may be evaluated as hands-on activities.

 

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This page constructed by Max Geisler
Max's Web Page
email Max Geisler

Last updated July 7, 1998

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