Scientific Method

A problem solving process:

1. Recognize a Problem

• This deals with asking the question “How does that happen?” or “How does that work?”

2. Forming a Hypothesis

• When you form a hypothesis you are making an educated guess towards the answer to your question or problem.

•A hypothesis is often stated “if….then….”

2. Hypothesis Cont.

• A hypothesis is often stated “if….then….”

3. Experiment

• When you test your hypothesis, you run an experiment.

•During the experiment you follow a procedure or series of steps.

3. Experiment Cont.

• You observe what happens, and collect data (facts and figures) during the experiment.

4. Conclusion

• The last thing to do is to look at the observations and data that you collected and summarize what happened.

•This summary is your conclusion.

Your conclusion can agree or disagree with your hypothesis.

Steps of ScientificMethod in order

State the Hypothesis

6

54

Make an Observation

the Problem

Determine

Limitations

9

Define the Problem

1

Analyze Data

2

Report Results

10

3

7 8

Experimenting

Let’s look at the text book example of the Scientific Method using Redi’s Experiment on Spontaneous Generation

He was trying to disprove the idea of SpontaneousGeneration (or actually that flies came frommaggots, which camefrom flies)

Francesco Redi Francesco Redi (1668)(1668)

Problem

Example: What creates maggots on meat?

Spontaneous generation once commonly accepted

Redi wanted to show what caused the appearance of maggots (and then flies) on meat

Belief based on prior observations

Redi observed that maggots appeared on meat a few days after flies were on meat

No microscope = no way to see eggs But Redi believed that maggots came

from eggs that were laid by flies

Hypothesis

Redi’s Hypothesis: Flies produce maggots.

How could he test this? Through a controlled experiment

Redi’s Controlled Experiment

Redi used two groups of jars -Jars that contained meat and no cover -Jars that contained meat and gauze cover

Jars with meat

Uncovered jarsCovered jars

Variables

Controls (Things that stay the same!): jars, type of meat, location, temperature, time

Variables(One thing you change): gauze covering that keeps flies away from meat

Let’s think about this.…

1. Which things stayed the same?

1. What one thing changed?

Let’s think about this.…

1. Which things stayed the same? Jars, meat, temperature, time.

2. What one thing changed? The cover.

OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.

HYPOTHESIS: Flies produce maggots.

PROCEDURE

Manipulated Variables:gauze covering thatkeeps flies away from meat

Uncovered jars Covered jars

Several days pass

Maggots appear No maggots appear

Responding Variable: whether maggots appear

CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

Controlled Variables:jars, type of meat,location, temperature,time

Redi’s Experiment on Spontaneous GenerationRedi’s Experiment on Spontaneous Generation

Data

Examine data tables, charts, and graphs

Examine experimental notes

Look for trends, patterns, and averages

What does the data show Put your data into words

Conclusion Hypothesis: Flies produce maggots. Conclusion: Only maggots were found in

the jars with the flies. Flies produce maggots.

Example: Problem: Will adding coffee grounds to a

plant make it grow faster? Hypothesis: If I add coffee grounds to a

plant, then it will grow faster.

Example: Controls: What things stay the same:

Example: Controls: What things stay the same: -type of plant -water amount -sunlight amount -temperature -soil

Example: Variable: What thing is changed: -coffee grounds

Exit: 1. What are the controls in an experiment? The controls are....

2. What is the variable in an experiment? The variable is the...