LENGTHY RELATIONSHIPS
© 1999 ENSI (Evolution & the
Nature of Science Institutes) www.indiana.edu/~ensiweb
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material may be copied only for noncommercial classroom teaching
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INTRODUCTION
Look around at people's feet. You will notice that some people have longer feet than others. Do the individuals with longer feet also have longer legs? Are people with longer legs taller? Are the number of strides a person takes in a given distance different when he/she is running or walking? Does the person's stride length change with speed? Would the same hold true for birds? For dinosaurs? For early hominids? Can patterns of the present give you clues to patterns in the past?
Your job is to answer the following questions using the following lab procedures. You will gather data from classmates and family members to determine if there is a relationship between foot length, leg length, and height. You will also measure your stride while walking and running. Use the following terms when taking your measurements:
foot length: distance from heel to toe (without shoe)
leg length: distance from the base of the heel (calcaneous) to the hip joint (acetabulem)
hip Joint: top of femur on the outside of the hip joint (To find this spot, lift your knee until your thigh is parallel to the floor. Feel for the hip joint in your buttocks area, put your leg down, and measure from that point to the floor.)
height: distance from floor to the top of the head
stride length: usually the distance from the back of the heel of one footprint to the back of the heel of the next foot, one stride step (sometimes two steps are considered on stride, for simplicity we will use one step is equal to one stride).
OBJECTIVES: TO FIND THE RELATIONSHIP BETWEEN:

A. Foot Length and Leg Length 
MATERlALS
Meter Stick, Data Table, Overhead Transparencies, Graph Paper
PROCEDURES
Part A
1. In your lab group, gather the following data and Record in Data Table 1. foot length, leg length, height (all measurements must be in centimeters)
2. Calculate the ratio of leg length (L) to foot length (F) for each group member and record in Data Table 1. (done for you in excel chart)
3. Calculate the ratio of leg length (L) to foot length (F) for each lab member and enter your results in Data Table 1.(done for you in excel chart).
4. For homework, combine the class data that was emailed into one spread sheet
5. Plot your data on Excel, use XY scatter and trend line.
Part B
1. Measure and mark off a distance of 1500 cm (15m) (D).
2. Walk the length while counting the number of strides (Nw). Record in Data Table 2.
3. Run the length while counting the number of strides (Nr). Record in Data Table 2.
4. Calculate the stride length (S) by dividing the distance (D) by the number of strides (N)
Stride walking Sw = 1500cm / Nw;
Stride running Sr = 1500cm / Nr
5. Measure and record your leg length.
6. Calculate the ratio of your stride length to leg length (S/L). Record in Data Table 2.
7. Graph (draw a graph using the data from as many people as possible, showing the relationship between stride length and leg length)
8. Repeat #6 and #7, but comparing stride with height (S/H)
9. Paste your graphs in your log book. (please use these graphs for the questions below: Lengthy Relationship Graphs (html) (doc)
CONCLUSION
1. Do you see a pattern on the graph? Explain.
2. Superimpose all (or several of) the group's graphs and determine if there are any relationships between the variables.
3. Determine if foot length can be used to predict height. Test you hypothesis by measuring a person's foot length and using your graphs to predict the height. Now, measure the height of that person. How close are you to the actual height? Calculate your percent error (difference between predicted and actual, divided by the actual, all times 100). Explain.
4. Pool the class data for the ratio of Leg Length to Foot Length. What is the average L/F ratio for people based on the class data?
5. Paleontologists use the ratio of stride length divided by leg length (S/L) to tell whether a dinosaur is walking, trotting, or running. Paleontologists use the following values to determine how a dinosaur might have been moving.
<2 walking 2  2.9 trotting >2.9 running
Examine the class data for the ratios of stride to leg length (Sw/L and Sr/L) to see if the values in the above chart would also apply to people.If not, what values would change?
ANALYSIS
1. If a person's footprints were discovered in someone's backyard, what information could be determined about the person who made the footprints? What information about the person could not be determined from the footprints?
2. If you had a dinosaur track way, how could you use the processes we learned in this activity to draw some conclusions about the dinosaurs which made the tracks?
3. Why did you count your stride over a 1500cm length rather than make only one stride measurement?
4. Below is a series of footprints found in the sand. Based upon the measurements given, calculate the leg length and height of the person. Who do you think the footprint belongs to male or female, adult or child? What information gathered during this activity allow you to hypothesize?
Foot Length = 29 cm; Stride Length = 160 cm