Highlight:

1
Highlight Scientists use many methods in their
research, such as descriptive investigation,
simple mathematical and engineering modeling and
design, and controlled experiments. Students
should learn a variety of methods to solve
problems and make sense of the world.
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• (6.2, 7.2, 8.2) Scientific processes. The student
  uses scientific inquiry methods during field and
  laboratory investigations. The student is
  expected to
• plan and implement investigative procedures
  including asking questions, formulating testable
  hypotheses, and selecting and using equipment and
  technology
• (B) collect data by observing and measuring
• (C) organize, analyze, evaluate, make inferences,
  and predict trends from direct and indirect
  evidence (7.2, 8.2)
• (D) communicate valid conclusions and
• (E) construct graphs, tables, maps, and charts
  using tools including computers to organize,
  examine, and evaluate data.

3
Experimental Design using Scientific Method
When scientists begin an experiment they use the
steps of the Scientific Method. You will be
asked to understand many of these steps on the
TAKS Test.
4
The Problem (in the form of a question) that the
scientists will try to answer, must be logical
and based on data or observations.
5
A prediction called a Hypothesis is next. It
must be a testable statement that you could
gather data to prove. (You cant measure which
is the prettiest, strongest, or best.)
Hypothesis Less than 500ml per week will slow
growth of ivy plants.
6
You must control an experiment. You can test
only one variable at a time. (How does the
amount of water effect plant growth? Keep the
light, containers, soil and plants the same.)
Controls Light, type of plant, amount of soil,
pot, temperature.
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400ml
500ml
300ml
A Control Group is the set-up that isnt changed.
(One plant gets the normal amount of water!).
Which group above is the control group?
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The independent variable is the thing you change
(amount of water). The dependent variable is the
result of the change you made(height of plant in
cm.).
Independent variable Amount of water given in
mm. Dependent variable Plant growth in cm.
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When reporting the results, the Independent
Variable is graphed on the X-axis. The Dependent
variable is on the Y-axis. DRY MIX Dependent
Responding Variable on Y-axis Manipulated
Independent Variable on X-axis
Growth in mm
Amount of Water
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The Conclusion must be supported by the data and
results you gather. To be valid, each experiment
needs a large sample size (grow 2000 plants in
each experiment) and must be repeated many times
in order to prove the Hypothesis (grow 2000
plants 100 times). If you are collecting
samples, in an experiment, do it randomly. Dont
take them all from one place.
Yes!
No!
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Check for understanding

• Check for understanding by answering
• the following questions.
• Remember that you are using the scientific method
  in investigations.

12
Which of these is a hypothesis that can be tested
through experimentation? F Bacterial growth
increases as temperature increases. G A fishs
ability to taste food is affected by The pH of
aquarium water. H Tadpoles fear of large insects
increases as the tadpoles age. J The number of
times a dog wags its tail indicates how happy the
dog is.
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The correct answer is A. Bacterial growth can be
measured. Dog happiness, fish fear, and tadpole
taste cannot be measured scientifically.
14
The table shows times required for water to
evaporate from identical containers. Which of
these is the best question to ask before
developing a reasonable hypothesis to explain the
data? A Does a lower temperature slow the rate
of evaporation? B What is the boiling point of
the water after both samples are heated? C Why
does water exist as a solid at -15C and as a
liquid at 25C? D How does the rate of
evaporation change when a different container is
used?
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The correct answer is A. The table shows data
taken to investigate temperature and the
evaporation of water.