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