‘Falsification Labs’
Teaching experimental skills.
John Welch, Cabrillo College
• Students want to get the ‘right answer’ in lab, but this
isn’t really how science is done.
• They ask: “Is my result close enough?” – meaning ‘do I
pass?’
• Where do they get this attitude? Chemistry Lab?
Previous school experience?
How do we train them to
‘think like scientists’?
• The only ‘right answer’ is careful investigation
that is well documented.
• Results that are inconsistent with theory are valid
and exciting, (once carefully checked).
• Decisions on consistency need to be made based
on statistical analysis.
November, 2005 paper in Physics Education
Lessons from experience:
• Statistical uncertainty concepts are necessary.
• Students buy the fake theories, even if they
know the ‘right’ answer.
• Students will think they did something wrong.
• Standardizing the experimental conditions
(initial height, angle, etc.) allows for group
collaboration.
“What did we do wrong?”
Steps in guiding them to discovery.
1. Is there really anything ‘wrong’?
- Can we say the results are ‘close enough’?
- Is the theoretical value within the confidence
interval agreed on by the class? (2 sigma, etc)
“What did we do wrong?”
Steps in guiding them to discovery.
2. Have them consider possible sources of error:
- Did you double check all measurements?
- How far off, and in which direction, would a
measurement have to be to account for the
discrepancy? Is that likely?
- Were there any shaky assumptions? If we didn’t
ignore friction, etc, how would results change?
“What did we do wrong?”
Steps in guiding them to discovery.
3. Check in with other researchers.
- Write your results on the white board.
- How does your data compare to those of other
groups?
- Is it likely that everyone made the same ‘mistake’?
- Is there a flaw in the experimental design?
“What did we do wrong?”
Steps in guiding them to discovery.
4. What’s left to consider?
- They’ll still say stuff like ‘human error’, etc.
- Some will start doubting the theory, and will notice
the funny names.
- Is it possible that the theory might not be right?
- After all your checking, would you be comfortable
telling a TV or newspaper reporter that you think
Floogle and Depew are wrong? (95% confidence)
- Call ‘authors’ on the phone to discuss results. 
Resources:
Falsification Lab activities available at Eric Ayars’
or my websites (google ‘Falsification Labs’)
http://phys.csuchico.edu/web/ayars/falsification/
http://www.cabrillo.edu/~jwelch/falsification/false.html
Please invent your own labs or modify these and
send them to Eric or John to add to archives.