Section 1: Scientific Method
Fundamental Topics in Science © 2001 Texas Instruments Teacher Notes 1-9
Activity—Variations in Human Heart Rate (cont.)
Generalize.
After entering the pulse rates and viewing the results, students are asked to state
the test conclusions, and then generalize about the effect of gender on heart rate. In a
WRITE IT
DOWN
screen, each student is asked to:
•
State the conclusions he or she can draw from the findings. Students might indicate that their
findings proved, disproved, or were inconclusive about whether the hypothesis was true or
false.
•
Discuss limitations. Students might mention such things as: inaccurate measurement of pulse
rate, small sample size, the variation of too many factors (activity level, etc.).
•
Discuss how well the results of the sample indicated rates in the class, the school, the
community, the world.
•
Discuss if the test indicated whether gender was the sole factor affecting heart rate.
•
Design a test for another factor.
Communicate.
Students share their findings and generalizations with the class. They should
describe in writing how their findings compared with those of other students.
Extension.
Encourage students to design (and perform, if time permits) investigations of other
factors affecting heart rate such as age, weight, physical condition, activity level, and heredity.
Remind them that, in general, results are easier to interpret if only one factor is varied at a time;
for instance:
•
Test 2: Measure one person’s pulse at varying levels of physical activity (sleeping, standing,
after running several minutes, etc.).
•
Test 3: Measure the at-rest pulse rates of several similarly-aged boys of varying weights.
To help students isolate factors, you might have them develop a chart such as the sample one
below. You can also discuss with students that not all factors are independent of each other,
such as weight and physical condition.
tested factor common factors variable factors
activity
gender age
activity level
weight
heredity
physical condition
test 2
activity level age
weight
heredity
physical condition
none
(all tests on one person)
test 3
weight gender
age
activity level
heredity
physical condition
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