by   Mimi Wallace  Harry Weekes   Nancy Wright   Carla Huffman

 
                        This activity correlates to Standard B of the National Science Education Standards
 

• Biology students
• Middle to High School Students

Notes to the Teacher: to top
Students will design an experiment dealing with stride length, perform the experiment and analyze the data.  We chose to use the Green anole for this, but other organisms might be selected.  Possible topics for experimental design include: the effect of surface texture on dimensionless speed; the effect of temperature; the effect of slope; the effect of mass.
Preparation time needed: minimal (depending upon the materials selected by students)

Class time needed: At least three class periods (40 minutes each).  One day for preparation and experimental design.  A second day for set up and collection of data.  A final day for analysis and conclusions.  It would be a good idea to get the anoles ahead of time so that students can observe and handle them.

Hazards:  While there are no hazards, good standard lab procedure should be followed at all times.

Helpful Hints:

• 1.) Speed data is hard to collect on anoles as they move erratically.  Student experimental designs should be checked for methods which most effectively deal with this variable.  If possible, motion detectors and computer imaging software should be used.
• 2.) If students are wanting to compare data taken from different animals they will need to plot their data on a graph which has the following:     x axis = the dimensionless speed
•                                                     y axis = relative stride length (stride length/leg length)
• 3.) Students should be instructed not to hold or grab anoles by their tails as they will fall off.  Anoles are delicate and bruise easily; rough handling may cause them trauma and stress.  An effective method of pacifying them is to handle them gently and often.  When students are comfortable handling the anoles they may try inverting them for a period of a few seconds which will cause them to 'fall asleep'.  In this state they can be measured and marked.  Holding them right-side-up will bring them out of this state.

• 4.) Anoles jump, be prepared for them to move off in both horizontal and vertical directions!  Having a loose cloth or shirt on hand to throw over the lizards will help in the recapture if they should 'escape'.
• 5.) If measuring stride length, an effective method of marking is painting one hind foot.  This can be done by rolling the end of a small test tube in paint and then rolling it onto the lizard's foot.

Other materials will vary based upon students' experimental design. For instance students may choose to test surface texture by utilizing sand, wood, Parafilm^TM and gauze.  If possible use of computers and motion detectors would be helpful as it is difficult to get anoles to move at a constant rate.
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Purpose:  With green anoles as the subject, you will design an experiment to test a component of the dimensionless speed equation which McNeill Alexander put forth in his book, Dynamics of Dinosaurs and Other Extinct Giants:
 
 Dimensionless speed = speed (m/s) 
                            (leg length (m) x gravitational acceleration (9.8 m/s²))

This equation is designed to produce a ‘dimensionless speed.’  In other words, knowing the speed at which the organism was travelling and its leg length will enable you to tell how quickly the animal was moving relative to any other organism.  Using speed and leg length is all that is necessary to measure dimensionless speed according to Alexander.
Equipment: you will be provided with the following:
Stopwatch
Meter stick
Ruler (with metric units)
Green anoles
Non-toxic, thick paint (assorted colors)
Small test tubes
Paintbrush
You are responsible for obtaining all other required materials.
 
Procedure: You will design an experiment to test a component of Alexander's deimensionless speed equation.  You will then carry out the experiment, collect data, analyze your results and prepare a formal lab report.  The lab report should contain: introduction, materials, procedure/methods, observations, data, analysis (graphs), conclusions and citations.

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