Scientific Method

Make an observation

Ask a questionForm a hypothesisCollect dataForm a conclusionForm a new

hypothesis and retest if needed

Communicate results

Quantitative vs. Qualitative

Qualitative data is any data that doesn’t involve a number. Examples:

The liquid turned blue. The shrimp started moving faster. The subjects got smarter.

Quantitative data is data that has a number or measurement attached to it. Examples

The pH went from 7.1 to 2.3. The shrimp moved its swimmerets 159 times in one minute. The subject’s IQ improved by 15 points.

Quantitative vs. Qualitative

In biology, scientists prefer quantitative data rather than qualitative data. Why? Quantitative data allows large amounts of data to be

easily compared and analyzed. Quantitative data allows experiments to be easily

repeated and compared.Qualitative data is still important and any

experiment should have both types of data.

Independent vs. Dependent Variables

What is a variable? A variable is any factor, trait, condition or quality that

changes in an experiment. For example: In our brine shrimp lab, we looked at two

main variables, the amount of water, caffeine or alcohol in the well and the number of beats of their swimmerets in a minute.

However, any thing that can vary in an experiment is a varible. For example: Other variables in our experiment include:

number of shrimp in the well, temperature of the water, age of the shrimp, or gender of the shrimp

Ideally, all variables than the two main variables you are experimenting with should be held constant.

Independent vs. Dependent Variables

The independent variable is the variable being manipulated or changed by the scientist.

The dependent variable is the observed result of the independent variable being manipulated. The dependent variable is the result that scientists are

most interested in in.For example:

In our brine shrimp lab, the amount of the various chemicals (water, caffeine and alcohol) being used is the independent variable.

The dependent variable is the number of swimmeret strokes per minute that we observed.

Independent vs. Dependent Variables

Scientific Theory

What is a scientific theory? A theory is a set of related hypotheses that have been

tested and confirmed many times by many scientists Examples of scientific theories:

The theory of gravity Germ theory The theory of plate tectonics

Scientific theory is not the same as “I have a theory about who murdered the duchess”!

Scientific theories are always testable and have lots of experiments to back them up.

Scientific Theory

A scientific theory means “ As far as we know, this is true”

Later experiments could disprove the theory. People used to believe

the Sun revolved around the Earth, but later experiments proved otherwise.