All Thumbs Lab Report


Scientific Method – “I’m All Thumbs”


What makes a “Class Champion” thumb wrestler? Does thumb diameter, length, or wrist diameter have an effect on the overall chances of winning a thumb-wrestling match? In this experiment, you will use the scientific method to find the answers to these questions.

The scientific method is a series of steps used to solve a problem. First, after making an observation, you form a question related to your observation. This is known as your problem. The next step of the scientific method is gathering data, information gathered to try to answer the question. Data may be gathered by more observations, sampling, measuring, and using quantitative data. It is important that your data is well organized.

Suggesting an explanation for what you have seen and observed or in other words, forming a hypothesis, is the third step. To test a hypothesis, you make a prediction that logically follows from the hypothesis. An experiment is often used to test a hypothesis. A controlled experiment is based on a comparison of a control group with the experimental group. These two groups are identical except for one factor called the independent variable. During the course of the controlled experiment, you will observe or measure another factor in both the control group and the experimental group. This is the dependent variable. After the data from the experiment is collected and organized, it must be analyzed. This is the process of determining whether data are reliable and whether or not they support the hypothesis or prediction.

The final step in the scientific method is drawing conclusions. Sometimes a model is produced to show your conclusion. A model is a visual, verbal, or mathematical explanation supported by data. An inference is a conclusion based on fact rather than on direct observations. Unlike a hypothesis, an inference is not directly testable. A theory may be formed after many related hypotheses have been tested and supported with much experimental evidence.


The girl with the largest total sum of thumb circumference, thumb length, and wrist diameter measurements will win the thumb-wrestling match.


To conduct this experiment, you will need: paper, pencil, a metric ruler, a metric tape measure, scissors, string, and a calculator. Six female students will be needed to act as participants in the match.


Choose a partner and perform the following measurements using the metric tape measure. Then have your partner take the same measurements on you. The first measurement taken is the circumference of the thumb, in centimeters, at its widest point. Record this data on a table. Measure the length of the thumb, in centimeters, from its tip to the end of its second joint. Record this data on the table, also. Measure the circumference of the wrist over the ulnar knob, in centimeters, and record this data on the table.

Gather the measurement data from the rest of the participants and record it in the result section of your lab report. Using the data you have gathered, form a hypothesis. You are now ready to conduct the thumb-wrestling matches. The rules for thumb wrestling are two players will grasp hands, touch thumbs to the opposite sides of the other person’s hand three times, then come out wrestling. The object of the match is to hold the other person’s thumb down for a count of three, using only your thumb. Boys will compete against boys and girls will go against girls.

A tournament schedule should be set up to match opponents. After the completion, a champion will be declared, one for the boys’ division and one for the girls’ division.


The results of the thumb-wrestling match are shown on a graph and a chart. Refer to the following chart and graphs for results of the experiment.

NameThumb CircumferenceThumb LengthWrist CircumferenceTotal of Measurements# of Wins
Stephanie H.6 cm6 cm15 cm27 cm0
Tori H.7 cm6 cm18 cm31 cm1
Carmesha J.6 cm7 cm17 cm30 cm0
Stephanie F.6cm6.5cm15.5 cm28 cm2
Krystal W.6cm6 cm16.5 cm28.5 cm3
Marlo S.6.1 cm6.5cm17.8cm30.4 cm1




1. Restate your hypothesis: The girl with the largest total sum of thumb circumference, thumb length, and wrist diameter measurements will win the thumb-wrestling match.


2. Which students won? (male) Brett Helms and (female) Krystal Wofford

3. What were their measurements:
male: thumb circumference: 8 cm, thumb length: 8 cm, and wrist circumference: 24 cm; female: thumb circumference: 6 cm, thumb length: 6 cm, and wrist circumference: 16.5 cm


4. What was the mean thumb circumference of the class? The mean thumb circumference of the females in the class was 6.2 cm.

5. What was the mean wrist circumference of the class? The mean wrist circumference of the females in the class was 16.8 cm.


6. Did all those with larger measurements win their matches? No, not all those with larger measurements won their matches.

7. Was your hypothesis correct? No, my hypothesis was not correct.


8. If not, explain what was different. The winner’s measurements were not the largest total.


9. What is the independent variable? Total of each contestant’s wrist and thumb measurements


10. What is the dependent variable? The number of wins for each contestant

11. List the controlled variables in this experiment. The controlled variables in this experiment the thumb wrestling rules followed by each contestant and only contestants of the same sex competed against on another.


12. Would this be considered a controlled experiment? No, this would not be considered a controlled experiment.

13. Explain you answer. There were too many variables (thumb length, thumb circumference, and wrist circumference) being tested at one time to see which one actually effected the outcome.


Error Analysis:
Students taking inaccurate measurements may have effected the results. Some of the participants in the wrestling match may have not followed the rules exactly. This could also effect the results. Testing so many variables at one time, with only one trial experiment, increased the chance of error.


Discussion and Conclusion:
The proposed hypothesis was incorrect. The female with the largest total measurements did not win the thumb-wrestling match. There was no consistent correlation between the total sum of thumb circumference, thumb length, and wrist circumference measurements and the number of wins. Additional experimentation is necessary to test the multiple variables in this experiment. Narrowing down the variables to one specific variable-thumb length for example-would possibly lead to a correlation between the number of wins and the variable being tested.