Transcript Brain Teasers… 1. Which soldier is the largest? 2. How many legs

Brain Teasers…
1. Which soldier is the
largest?
C
B
A
2. How many legs
does this elephant
have?
INVESTIGATION AND EXPERIMENTATION
(I & e) :
What is “Science”?
Observations, Inferences, and
Controlled Experiments
1. Science is an attempt to explain natural
phenomenon.
2. All scientific knowledge is based on
accurate observations of the natural world.
3.
-An Observation an act of carefully watching
something and collecting facts.
-Observations are:

Gathered by using our senses (qualitative)

Can also be gathered by taking measurements
(quantitative)
-Characteristics of good Scientific Observations:

Accurate – Quantify or measure whenever possible

Detailed and Complete – Consider all parts of the
observation

Repeatable – All observers see the same thing or
each time the event is observed the description is
the same
4. There are two types of observations:

a) Qualitative Observations—An observation
that describes the physical characteristics or
qualities of something.
(Ex. The water is hot; The M&M is small; The egg
smells bad; The leaf is orange, etc)

b) Quantitative Observations—An observation
that is based upon numerical information or a
measurement of some type.
(Ex. The water is 45ºC; The M&M is 1.7 cm in
length; The car is traveling at 65 Km/hr)
5. Good scientific observations are used in
order to make predictions, or inferences,
about the natural world.
6. To infer means… to make a prediction based on
observation.
7. An inference is a conclusion that is formed by
using logic and what is previously understood
about the natural world.
Ex
Which statement is an inference?
a. It has 3 candles.
b. It is a cake for some one turning 3 years old.
c. It is a round cake with squiggly black lines.
8. Good scientific inferences:
a) Consider all available observations.
b) Fits the understanding of the natural world
c) are the most logical and rational conclusion.
9. All inferences must be based on previous
observations of the natural world.
10. Inferences are the basis for all Scientific
Theories and Hypotheses.
11. What’s the difference?
Theory v. Law v. Hypothesis
**A scientific theory is a well-tested
explanation that unifies a broad range of
observations.
(Ex: Theory of Plate Tectonics, Evolution, Cell Theory, Germ Theory,
etc.)
-A
scientific theory may be revised as new
evidence is presented.
-A theory is like the automobile.
-WHY?? Components of it can be changed or improved upon, without changing
the overall truth of the theory as a whole.
**A scientific law is a consistent principle that is
repeatedly observed in nature and is usually
mathematical.
-It is always true.
(Ex: Gravity, Speed of light, Newton's laws of motion, the laws of
thermodynamics, Boyle's law of gases, the law of conservation of mass and
energy, and Hook’s law of elasticity. )
A scientific law is like a slingshot.
WHY?? A slingshot has but one moving part--the rubber band. If you
put a rock in it and draw it back, the rock will fly out at a predictable
speed, depending upon the distance the band is drawn back.
12. Scientific Method and Controlled Experiments
**A hypothesis is a testable possible
explanation of an observation.
-In science, a hypothesis is useful only
if it can be tested.
-Scientific hypotheses are most often
tested by the process of
experimenting.
An attempted explanation needs to be
tested to be accepted.
Scientific Method
I. State the Problem
II. Form a Hypothesis
III. Set up a Controlled Experiment
IV. Record and Organize Data
V Formulate a Conclusion
Scientific Method
I. State the Problem— Form of a
question that indicates the purpose of
the investigation.
II. Form a Hypothesis— This is a
possible explanation or answer to the
problem/question presented.
(Hypotheses are not proven but
supported by evidence)
*III. Set up a Controlled Experiment—
An experiment is basically a comparison of two
situations.
One of the situations is left constant, while one
factor of the other situation is changed in order
to test the affect of that specific change.
Control – a set of conditions used for comparison
purposes; can either be original conditions, real-life
conditions, or specific conditions set by the experimenter
There are three types of factors that may affect an
experiment. These factors are called variables.
1. The factor that is purposely changed by the experimenter
is called the independent variable
(also called the manipulated variable).
2. The factor that changes in response to the independent
variable is called the dependent variable
(or the responding variable).
3. The rest of the factors that the scientists keep the same
in the experiment are called the controlled
variables.
It is important to test the affect of changing only
one variable in order to get accurate results.
**If only one variable is changed and all the other
factors are kept the same then we say that it is a
controlled experiment.
***Uncontrolled conditions can lead to inaccurate
results.
IV. Record and Organize Data—
- Data tables, graphs, charts, observations, etc.
V. Conclusion—
- Indicate whether or not your hypothesis was
correct
- Describe how the data provides evidence for
your conclusion
- Identify possible sources of error in your
experiment
Practice Problem :
Krusty was told that a certain itching
powder was the newest best thing
on the market, it even claims to
cause 50% longer lasting itches.
Interested in this product he buys
the itching powder and compares
it t his usual product. One test
subject is sprinkled with the
original itching powder, and
another test subject was sprinkled
with the experimental powder.
Subject A = 30 min itches
Subject B = 45 min itches
Identify the:
35. Control group -
why?
36. Independent variable -
why?
37. Dependent variable -
why?
Two Students were testing the
amount of fertilizer that would best
promote the growth of strawberries
in a garden. Which could be
unavoidable sources of error?
A.
B.
C.
D.
Length of study
Variation in the strawberry plants
The cost of watering the plants
Fertilization during the study
In most stable freshwater
environments, populations of Daphnia are almost
entirely female and reproduce asexually.
However, males are observed in low oxygen
environments or when food is scarce. Based on
these observations, a researcher suggests that
male Daphnia develop in response to unfavorable
environmental conditions. This is an example of a
A.
B.
C.
D.
Result
Theory
Procedure
hypothesis