Scientific Method – Chp 1 -2
NOT a series of steps that HAVE to be followed in a specific order every time- depends on the question you are
trying to answer!
BUT in GENERAL!
1. MAKE AN OBSERVATION
a. observation – gathering information using tools or senses
b. inference – a judgment based on your reasoning from evidence
- see smoke, infer there is a fire (but maybe not- could be grilling)
2. ASK A QUESTION
3. FORM A HYPOTHESIS & PREDICTION
a. hypothesis – a possible explanation for the solution to a problem using what you know and
observe
- must be able to be TESTED
b. prediction – statement of what will happen in a sequence of events based on the hypothesis
= stated as an “if-then” statement
EX: Hypothesis: When logs burn, new substances form because matter cannot be created or
destroyed
Prediction: If logs burn, then the substances that make up logs will change into a new
substance
EX: Hypothesis: The deformities of frogs in a MN lake were caused by 1 or more chemical
pollutants
Prediction: IF a substance in the water caused the deformities, THEN the water from ponds
that have deformed frogs will be different from the water from ponds in which no
abnormal frogs have been found
EX: Hypothesis: The frog deformities were caused by attacks from parasites or other frogs
Prediction: IF a parasite caused the deformity, THEN this parasite will be found more often in
frogs that are deformed.
EX: Hypothesis: The frog deformities were caused by an increase in exposure to UV radiation from
the sun
Prediction: IF an increase in UV radiation exposure caused the deformities, THEN some frog
eggs exposed to UV radiation in a lab will develop into deformed frogs
4. CONDUCT A CONTROLLED EXPERIMENT (tests a hypothesis)
a. controlled experiment – procedure in which you gather data by controlling or keeping constant
all the variables that could affect the outcome of the experiment
except the one you want to test or measure
-tests the effect of 1 thing on another – CAUSE & EFFECT
Usually involves 2 groups
Control Group
-“normal” group, nothing is changed
-used as a comparison
Experimental Group
-identical to control with ONE thing changed
- is compared to the control
b. 4 parts of an experiment
1. control – the standard used to compare the experimental group
-it shows that our result is related to the condition you’re testing for and not some
random event
2. constants –all the factor between the two groups that don’t change in an experiment
3. independent variable – the ONE factor that is changed or manipulated by the
Experimenter
“
I change the Independent variable”
(both have “I’s)
- Independent variable is placed on the x axis of a graph
4. dependent variable – factor whose value depends or responds to the independent
variable
-data is placed on the y axis of a graph
“DRY MIX”
Dependent variable – Responding variable – on Y axis
Manipulated variable- Independent variable – on X axis
5. Record and Analyze Data
a. data- any and all recorded observations and measurements
quantitative data: measurements; use numbers; 6m, 50 sec, 10 kg
qualitative data: describes something; uses words – red, rough, square
a. may be recorded in a graph, table or chart
b. graph: visual representation of information – makes it easier to understand & see relationships
3 types of graphs:
1. Line Graph – shows trends or how data changes over time
2. Bar Graph – compares information collected by counting
3. Pie Graph – Shows how a fixed quantity is broken down in parts
6. Conclusion
a. conclusion – judgment based on interpreting observations and data
b. may or may not support hypothesis
c. bias: a certain way of thinking that may change how the data is interpreted & conclusions made
-every effort should be made to reduce bias
d. model – a symbolic representation of an idea, system or structure to make something
easier to understand
1. they help us solve problems & deal with things that are hard to see because they
are too large or too small and help us MAKE PREDICTIONS
2. can be physical, mathematical
-physical : like a cell model, or atom model, or solar system model - drawings
-mathematical – equations
7. Repeat your Work and Communicate
a. work must be repeated many times by different people before it will be accepted
b. work must be shared so others can replicate and confirm results –
D. Theories & Laws
1. Theory
a. theory – explanation based on many observations and supported by data (YOU aren’t going to
have a theory!)
b. a theory is the most logical explanation for why things happen
c. a theory explains the how and why of laws
Ex) theory of evolution – animals change through natural selection because of competition
d. a theory can be changed as new information is discovered
2. Law
a. law – a ‘rule of nature’ that summarizes related observations and data that describes a
pattern in nature – it is a “natural law”
-laws describe what happens (not how or why)
-don’t usually change
Ex) Law of Gravity= force of attraction between all objects
To Know:
Understand and explain the scientific method and why it’s not a rigid set of steps that always has to be followed
Difference between an observation and an inference
The parts of an experiment
Difference between an independent and dependent variable
Difference between a hypothesis and prediction but know how they are related
Difference between an experimental and control group and the purpose of each
Difference between quantitative and qualitative data
Types of graphs and when each are used
What are models and why are they used
What bias is and how it can affect conclusions
Difference between hypothesis, law, and theory
Terms:
Bar graph
Independent variable
Bias
Inference
Conclusion
Law
Constant
Line graph
Control group
Model
Controlled experiment
Observation
Data
Pie graph
Dependent variable
Prediction
Experimental group
Qualitative data
Graph
Quantitative data
Hypothesis
Theory