Transcript Are mealworms affected by light?

What does science mean
to you???
This power point and the copyrighted images within it
may not be reproduced or distributed except for
normal classroom use.
Science is a way of knowing
about the natural world,
using a process,
designed to reduce the chance
of being misled.
Everyone does science
(or should)
You don’t have to have a PhD to
do science,
you just follow some basic steps
and rules.
An example of the 8 Steps
in the Process of Science
You come home one night,
flip on the light switch,
and nothing happens.
1. OBSERVATION
The light doesn’t turn on
2. QUESTION
Why didn’t the light turn on?
Keep the question open-ended. For example, don’t ask “Did the light
not turn on because the bulb is burned out?”
3. LITERATURE REVIEW
Find out what lights require to
function and what can cause
them not to function.
Lights need
electricity
to work
4. MULTIPLE HYPOTHESES
What are all the possible
answers (hypotheses) to
the question?
H1: Power is out to the house
H2: The light bulb is burned out
H3: The lamp is broken
You need to think of many hypotheses to avoid
jumping to a conclusion
5. DEDUCTIONS
For each hypothesis, determine what evidence (data)
would be required to refute or support the
hypothesis? In other words, what would we expect
to observe if we conducted a test.
H1: Power is out to the house
Example Deduction for H1:
If the light did not turn on because the power
is out to the house…
then … I would expect no other electric
appliances to work in the house.
5. DEDUCTIONS
H2: The light bulb is burned out
Example Deduction for H2:
D2) If the light did not turn on because the
light bulb is burned out…
Then… the bulb will rattle when shaken
Then… a new bulb will work
5. DEDUCTIONS
H3: The lamp is broken
Example Deduction for H3:
D3) If the light did not turn on because
the lamp is broken
then… a new light bulb will not work.
6. TESTS/ EXPERIMENTS
Conduct tests to collect actual data
Examples:
1) Turn on other appliances
2) Shake the light bulb record sound
3) Try bulb in a functioning lamp
7. TENTATIVE CONCLUSIONS
Which hypotheses were supported and
refuted by the actual data?
H1 refuted: Other appliances worked
H2 supported: Bulb rattled when shaken
H3 refuted: New bulb did work
Tentative Conclusion: Light bulb was burned out
Test H2 again by putting “burned out” light bulb in
a functioning lamp!
8. PEER REVIEW
Submit your report to a scientific journal.
Scientists whose reputation is at stake, and chosen
by the journal editor, will determine whether your
report is scientifically sound and should be published.
The Scientific Method
1. Observation
4. Multiple
Hypotheses
5. Deductions
2. Question
3. Literature Review
6. Tests
8. Peer Review
7. Tentative
Conclusions
Science Rules of Thumb
1. Maximize Sample Size:
The larger the sample size the more accurate the
estimate. [Have sample sizes in the thousands or more
if possible]
2. Representative Sample:
The sample must represent the variation in the whole
population. E.g., Use random or systematic sampling to
avoid biasing the data.
E.g., you don’t want your sample to include only men if you
are studying the effect of a medicine on people.
Science Rules of Thumb
3. Use Controlled Experiments for Causal Questions
Use to answer questions concerning what caused
something to happen. Two groups (control &
experimental) are treated identically except for the one
factor being tested. If the results are different
between the experimental and control groups, then one
knows that the change was caused by the single factor
that differed between the two groups.
Science is NOT just facts
Science does NOT answer right
and wrong questions
Science does NOT prove
Some Definitions
Hypothesis = a possible explanation for an observed
phenomenon
= a possible answer to a question
– Must be able to generate testable deductions
Theory = conceptual framework that explains a variety of
observations, is supported by experimental evidence and is
capable of predicting new phenomena
= as sure as science ever gets
–Not “just a guess,” as used in everyday language
Examples of theories?
– Theory of relativity
– Theory of evolution by natural selection
– Theory of plate tectonics
MEALWORM MYSTERY
This is just for fun to test your understanding of
controlled experiments
• A student conducted 3 experiments to
determine how mealworms respond to
light and moisture.
• All variables except light and moisture were
held constant from experiment to
experiment.
• For each experiment, 12 mealworms were
placed in the center of a box and then their
positions were recorded 24 hours later.
EXPERIMENT 1
mealworm
QUESTION: Are mealworms attracted to
light?
QUESTION 2: Are mealworms affected by
moisture?
Answer?
You can’t tell; it could be either
or both
EXPERIMENT 2
QUESTION: Are mealworms affected by
light?
QUESTION 2: Are mealworms affected by
moisture?
Answers? They are affected by light; we
don’t know about moisture
EXPERIMENT 3
QUESTION: Are mealworms affected by
light?
QUESTION 2: Are mealworms affected by
moisture?
Answers? With just this experiment, it
seems they didn’t move
EXPERIMENT 3
Using the
information
from the
other 2
experiments…
QUESTION: Are mealworms affected by
light?
QUESTION 2: Are mealworms affected by
moisture?
Answers? Yes and Yes (despite attraction
to light, they avoided wet
THE EXPERIMENTS
1
mealworm
3
2
Without the
controlled
experiment we
would know
nothing!
QUESTION: Which variables affect mealworm movement
based on the above experiments (note that movement may
be either toward or away from something)? A. Light but not
moisture. B. Moisture but not light. C. Both light and
moisture. D. Neither light nor moisture. E. Can’t tell.