Left-Handedness: A Science Project

Complexity level:	4
Time required:	1 hour to prepare, 3 days for the science project experiment
Material availability:	Easily found
Safety concerns:	None

Hypothesis

Left-handed persons will form less than 10% of the total number of persons surveyed, based on various sources of research/documentaries.

Overview

Left-handedness

A left-handed person tends to prefer to use of his left hand over the right hand to perform their daily chores. Left-handed persons constitute less than 10% of the population. Left-handedness is a hereditary trait. Normally a left-handed person is not alone in the family. Either one of the parents, an uncle or an aunt will also be left-handed.

Scientists believe that left-handed persons and right handed persons are “controlled” by different sides of the brain. The right handed person is supposed to be controlled by the left side of the brain and the left-handed person by the right side of the brain. This is because the nerves from the brain actually crossover to the other side of the body near the neck area.

Scientific Terms

Hereditary, brain, nerves, left-handedness

Materials

The materials required for this science fair project:
- A registration book for students to write their names
- A pen
- An authorization letter from the school principal, granting permission to meet with all the students in their classrooms
- A register of all the student names, in each class

Procedure

1. For this experiment, the independent variable is the student’s class. The dependent variable is the number of kleft-handers. This is verified by observing them when they write their names. The constants (control variables) are the age of the students and the gender ratio (the ratio between boys and girls) of the students. You should ensure that the classes consist of students of the same age, and an equal mix of boys and girls.

2. Two classes will be visited each day.

3. The students are requested to write their names in the registration book one at a time. While they are writing, observation is made, of the hand they use to write. This is recorded in the registrar containing all the student names.

4. Procedures 3 and 4 are repeated with the remaining 5 classes over 3 days.

5. Once all the students in the 6 classes have written their names, the number of right handed students and left-handed students in each class is recorded in the table below. The total number of students is also recorded in the table.

6. The percentage of left-handed students is calculated as shown in the formula below and recorded in the same table.

Percent of left-handed student = (Number of left hander in class)/ (Total student in class) x 100%

Results

It is observed that the total percentage of left-handed students among the 12 year olds in the school was only 6.3%. The students who were able to write using either hand were regarded as a right handers.

Category	Total no. of persons surveyed in each class for 12 year olds	Total
Class 1	Class 2	Class 3	Class 4	Class 5	Class 6
Right handed	37	35	37	39	38	37	223
Left-handed	4	3	2	3	1	2	15
Total number of student	41	38	39	42	39	39	238
Left-handed %	9.76%	7.89%	5.13%	7.14%	2.56%	5.13%	6.30%

The chart below represents our observations:

Left-handers science fair project

Conclusion

The hypothesis that left-handed persons form less than 10% of the total number of persons surveyed is proven to be true.

Left- handed persons live in right handed world. Almost all consumer items that are mass manufactured, are meant for a right- handed society. Basic tools and items like scissors, pliers, door knobs, buttons on a shirt, musical instruments and sports equipments are all designed and mass produced for the right handed majority. However left-hander takes pride in being part of the company of great minds including the likes of Leonardo da Vinci and Michelangelo!

Also consider

Perhaps not all persons who are left-handed are also left-legged. Conduct another survey to find out how many left-handed persons kick ball with their left foot.

Conduct another survey on how many persons can fold their tongue.

References

Left-handedness - http://en.wikipedia.org/wiki/Left-handedness

Why are some people left-handed? - http://www.coolquiz.com/trivia/explain/docs/lefthand.asp

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