Introduction to Biology

What is the Scientific Method?

Scientific Method:

A logical, systematic way to solve problems

What does “systematic” mean?

6 Steps1. Observe/State the Problem2. Gather Information3. Hypothesis4. Experiment (or test)5. Analyze Results6. Conclude

Observations

• Can be Qualitative or Quantitative

Qualitative: characteristics (color, texture, smell, shape, etc)Quantitative: numbers/you can count

Examples:

Qualitative:I see yellow, fuzzy ducklings.The milk is foamy and has a sour smell.

Quantitative:There are 42 geese in the flock.

Hypothesis

Must Be:Measureable (can you test it?)Can be verified or falsifiedMakes a prediction (about outcome)

Why is this a BAD hypothesis?

1. Dogs are happy when you feed them steak?

2. There are planets in other solar systems that have life.

3. Cows produce more milk if you feed them 3 times per day and play classical music to them while eating.

Why is this a GOOD hypothesis?

1. Five milligrams of calcium per day will give mice stronger bones.

2. Cedar trees grow best in nitrogen-poor soil.

Good Experimental Design:

A well designed experiment will have:Control Group: does NOT get the test;

does NOT change

Test Group: DOES get the test; DOES change

Variables

Types of Variables

Independent Variable: the variable that you PURPOSEFULLY change or manipulate

Dependent Variable: the response that occurs due to the independent variable;is what you MEASURE

Controlled Variables

or Controls or Controlled Factorsare those elements in the experiment that DO NOT CHANGE

Let’s Practice

Look at Board!