Transcript The Scientific Method

Universal approach to problem-solving in science!!
 Will
the caffeine in coffee prevent mold growth?
 Does temperature affect the rate of diffusion?
 What wavelength of light do plants photosynthesize
the best under?
 What brand of diapers is the most absorbent?
 Go
to library to find out what other similar
questions scientists have asked and what
conclusions they have come to.
A
testable explanation for a question or
problem.
 “an educated guess”
 “If plants reflect green light, then the rate of
photosynthesis will decrease under green
wavelengths of light."
Procedure that tests the
hypothesis
 Controlled Experiment –
has 2 groups:




Control group: all
conditions are kept the same
for comparison purposes
Experimental group: “test”
group(s), only a single factor
is changed = INDEPENDENT
VARIABLE.
The change that results is
called the DEPENDENT
VARIABLE.
A team of students hypothesized that seeds would
germinate faster at warmer temperatures. They divided 50
radish seeds into 2 identical pots and held all conditions –
light, water, fertilizer- the same except for temperature.
One pot was kept at 18oC and the other at 25oC. They
measured the number of seeds that germinated over 10
days.
 Independent
Variable ??
 Did you say temperature?
 Dependent Variable??
 Did you say # of seeds germinated?

A scientist hypothesized that tobacco plants would grow better
with fertilizer. He took identical seeds, put in identical pots,
watered the same amount, gave them the same amount of light,
etc. The only thing different between the two plants was that one
had fertilizer added to the soil and the other did not. He could
then measure their growth.
 Independent
 fertilizer
 Dependent
 Rate of growth
Variable ?
Variable ?
 Control Group ?
 One without fertilizer
 Experimental
 One with fertilizer
Group ?
 Use
your 5 senses to make OBSERVATIONS:
a. Quantitative = # ( 5 cm.)
b. Qualitative = subjective (tan in color)
 Usually recorded in tables, graphs, charts,
etc.
 Report
& publish results… when a scientist’s
data supports the hypothesis & it is
supported by additional
experiments….becomes a THEORY.
 For example, the cell theory.
 If hypothesis is not supported…reject or
revise, ask new questions and test again.