Scientist think and talkLanguage of Science
* Are you hyperactive or hypoactive today?
Thinking about thinking
• What are the numbers on the bottom of the dice?
• How do you know?
Scientific Method &Experimental Design
Solving Problems• To answer questions scientists use
an organized system called the Scientific Method:
• Some questions are solved quickly• Some over years • Some never get solved
Basic SM• Question • Test • Analyze • Conclude
Steps of the Method• State a problem• Gather information (research,
observations)• Form a hypothesis• Perform an experiment to test the
hypothesis• Record & analyze data• State a conclusion• Repeat the work
Creating a Hypothesis • Based on a small amount of information• An If – Then -- Because statement • Needs to be testable • Needed for experimentation
Make a hypothesis• You notice that your scores on your tests
in biology over the past month. You want to improve your test scores.
• Form a hypothesis:
Where to Start• To get precise results that are
accepted by other scientists, you need:
– a specific hypothesis
– design a specific experiment
Parts of an experiment• In an experiment there are two
variables
– Independent variable– Dependent variable
Independent variables • This is the part of the experiment
that is deliberately changed from the beginning of the experiment
• The factor that is being tested
Trials & Sample Size• Set up multiple trials based on the IV
– Everything is the same except the factor being tested
• Make sure to test more than 1 per trial – Why?
Dependent variable• This is the part of the experiment that is
measured
• This measurement tells the scientists if the independent variable has an effect on the outcome of the experiment
• 2 kinds:– Quantitative & Qualitative
Designing of Experiment• In addition to the variables some
experiments allow for a control– An experiment where there is not IV
The Control• Makes sure that the experiment tests
the independent variable
• How?– Hold all factors at “normal”
• Used for comparison
The Results• Results either support or disprove
the hypothesis
Scientific Hypothesis• A possible explanation for an observation
based on a small amount of information
Scientific Law• A basic principle that describes behavior
of a natural phenomenon. A rule of nature. Explains what will happen.
Scientific Theory• A well tested explanation, supported by an
overwhelming amount of evidence & is accepted by the majority of scientists. Explains Why
• Often used to explain scientific laws
Practice your skills
• Identify the various elements of scientific method
AND
• Identify experimental errors
Scenario 1
• Compost and Bean Plants– Different aged grass compost on bean plant
growth– Older compost should produce taller bean
plants– 3 flats (25 plants per flat): Flat A given 6
month old compost, Flat B given 3 month old compost and Flat C no compost
– Plant height recorded after 30 days
Scenario 2
• Metals and Rusting– Utilities company burying lead next to iron pipes to
prevent rusting– Perhaps more active metals will be better at
preventing rusting– Placed following into separate beakers of water: a) 1
iron nail b) 1 iron nail wrapped in aluminum c) 1 iron nail wrapped in magnesium d) 1 iron nail wrapped in lead
– Same amount of water used in each and at end of 5 days rated amount of rust
Scenario 3
• Certain perfume esters agitate bees, wanted to know if Ester X was present in 4 different perfumes by observing bee behavior
• Placed 10 mL of first perfume 30 m from hive, recorded time for bees to emerge and behavior
• Allowed for 30 min recovery then repeated with additional perfumes
Scenario 4
• Fossils and Cliff Depth– Observed that different types and amounts of
fossils were present in a cliff behind home– Marked bank at five positions: 5, 10, 15, 20
and 25 m from surface– She removed 1 bucket of soil from each of the
positions and determined kind and number of fossils in each sample
Scenario 5• Aloe vera and Planaria
– Aloe vera is to promote healing of burned tissue so it might help with regeneration of planaria.
– Bisected planaria to obtain 10 parts (5 heads and 5 tails)
– Applied 0%, 10%, 20%, 30%of aloe vera to the groups
– 15 mL of solutions were applied. All planaria kept in same chamber with same temp, food, etc
– On day 15 Jackie observed the regeneration and categorized as full, partial or whole
Scientific Theory• A well tested explanation, supported by an
overwhelming amount of evidence & is accepted by the majority of scientists. Explains Why
• Often used to explain scientific laws
SCIENTIFIC METHODand the Snowshoe Hare
• Observations – • Problems (?)-• Hypothesis – • Manipulated (Independent) Variable –• Responding (Dependent) Variable –• Control Group• Constants