Transcript scientific method 7th grade

Scientific Method
Observation - Using the five senses to observe
anything in nature
2. Hypothesis - a statement that both explains an
observation and can be tested
3. Experiment - test carried out on the hypothesis
1. Equipment - what you used in the experiment
2. Method - procedure or how you did the
experiment
4. Conclusion - restate your hypothesis, summarize
your method, did you prove or disprove your
hypothesis and summarize your results
1.
How are Hypotheses Written?


Are the following Hypotheses?
1) Ultra violet light may cause skin
cancer.
2) Temperature may cause leaves to
change color.
Yes but they are not very useful.
They do not tell us how we are
going to test the observation.
How are Hypotheses Written?
 Temperature
may cause leaves to
change color.
 To rewrite this in a usable hypotheses
use an If …. then statement.
 Example
If leaf color is related to
temperature then exposing plants to
low temperatures will results in
changes in leaf color.
How are Hypotheses Written?
 A hypothesis
will have a
dependent variable and an
independent variable
 Dependent variable is the variable
you observe.
 Independent variable is the
variable you change.
How are Hypotheses Written?
 Rewrite
the following hypothesis.
Ultra violet light may cause skin
cancer.
If skin cancer is related to
ultraviolet light then people with
high exposure to ultraviolet light will
have a higher frequency of skin
cancer
Designing an experiment
 Lets
design an experiment around
baking bread.
 Observation
Bread rises when it is mixed
and then baked. Why?
Yeast consumes sugar and
gives off CO2 which causes the
bread to rise.
Form a Hypothesis
If more sugar is added, then the
bread will rise higher.
Identify the two variables in the
Hypothesis
Independent Variable
The independent, or
manipulated variable, is a
factor that’s intentionally varied
by the experimenter.
In this experiment we are going
to use 50g., 60g., 70g., 80g.,
90g. of sugar in this
experiment.
Dependent Variable
The dependent, or responding
variable, is the factor that may
change as a result of changes
made in the independent
variable.
In this case, it would be the size
of the loaf of bread.
Control Group
In a scientific experiment, the
control is the group that serves
as the standard of comparison.
The control group may be a “no
treatment" or an “experimenter
selected” group.
Control Group
The control group is exposed to
the same conditions as the
experimental group, except for
the variable being tested.
All experiments should have a
control group.
Control Group
We will select 50g. of sugar for
the control group since this is
the recipe standard
Constants
The constants in an experiment are all
the factors that the experimenter
attempts to keep the same.
What could be some of the constants in
this experiment?
Constants
They might include:
Other ingredients to the bread recipe, oven
used, rise time, brand of ingredients,
cooking time, type of pan used, air
temperature and humidity where the bread
was rising, oven temperature, age of the
yeast…
Which group
performed the
best?
Size of Baked Bread (LxWxH) cm3
Size of Bread Loaf (cm3)
Trials
Amt. of
Sugar (g.)
1
2
3
Average
Size (cm3)
50
1296
1440
1296
1344
60
1404
1296
1440
1380
70
1638
1638
1560
1612
80
1404
1296
1296
1332
90
1080
1200
972
1084
Control group
Write a Conclusion
Restate your hypothesis restate your
method and did your experiment support
or not support your hypothesis.
 Write a conclusion to the bread
experiment in your notebook.

Practice
Pick up the first hand out and read the
various experiment and identify the
independent, dependent variables and the
control in each.
 When finished give the second handout a
try

Experiment
Write out your procedure for the
experiment along with a materials list.
Collect and Analyze Results
You comes up with a table so
you can use it to record your
data.