GENETIC VARIATIONS IN HAND SPAN SIZE
RICHARD CHILTON CHICAGO VOCATIONAL HIGH SCHOOL
2100 EAST 87TH STREET
Students shall measure their handspan size to determine if one pair or many
pairs of genes control that trait.
Metric rulers, Basketball, Lab. Worksheet, Graph paper, and Graphic
Obtain a metric ruler, lab. worksheet and graph paper. Measure your
handspan size as demonstrated by teacher, spreading out your hand on a
sheet of paper. Draw a line from the tip of your thumb to the tip of your
little finger. Do not include length of fingernails. Measure the length
of the line (your handspan) in millimeters. Record the measurements of
all members of your class on the chalkboard. Organize the measurements into
a graph showing handspan size in groups of 5 mm. Also record the number of
students in each group. Draw a graph of the data in the table. Then carry
Basketball out to students to see if students can place handspan across the
Basketball and hold in place without touching any object. Next, answer the
(1) What does the graph reveal about the differences in handspans within
(2) Based upon these data, do you think size of handspan size is
controlled by one or more pairs of genes?
(3) What other factors can affect hand size?
Conclusion: If a genetic trait is controlled by a single pair of genes,
then class results would usually show only two categories or groups. When a
genetic trait is controlled by several pairs of genes, a number of
different groups will appear. Therefore, this genetic trait must be
controlled by more than one pair of genes.
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