Doing Science: The Scientific Method

Chapter 1-2

Science 8

What are two types of research?

Descriptive research Solve problems by

observation

Experimental research Solve problems by

testing hypothesis through use of carefully controlled steps

List the steps of descriptive research.

Research objective What you want to find out

Research design How investigation will be

carried out How data recorded and

analyzed

Bias Avoid bias Careful measurements Random samples

What are steps of experimental research design?

Scientific Method Step-by-step

approach to help scientists find solutions to problems

What are the steps of the Scientific Method?

Purpose Hypothesis Experiment Analysis Conclusion

Step 1. Purpose “What do I want to find out?”

Questions come from: Reading an article in a

book or magazine Interesting observations Thought about a

scientific phenomenon Conclusions from

another experiment

Purpose of the experiment should be specific

Problem should be something that can be solved through experimentation What is the average

number of seeds found in apples?

Does the color of a surface affect it’s temperature?

Practice Time Identify if the following questions would

be appropriate for scientific investigation.

Which has more fries—a large McDonald’s French fry or a large Sonic French fry?

What is the average number of pine cones on a branch of a pine tree?

What happens if you do not eat breakfast?

Step 2. Hypothesis Idea to a solution for a

problem Educated guess

Based on knowledge/research

“This is what I think will happen.”

Written as an “If…then…”statement “if” is the part the

scientist will change on purpose

“then” is the result of the change

Hypothesis examples.

IF fertilizer is added to a plant, THEN it will grow taller

IF a player attends batting practice, THEN their batting average will improve.

Practice Time!!Write a testable hypothesis for each of

the following questions.

How does advertising for the aluminum can collecting week affect the number of cans collected?

If we advertise for the aluminum can collecting week, then we will increase the number of cans collected.

How does the depth of a lake affect it’s temperature?

If we measure the lake at different depths, then we will find that the temperature decreases as we get deeper.

Step 3. Experiment Testing of the

hypothesis to see if it is correct

During an experiment, the following must be done:

1. Decide which variables and controls will be used Control—standard that

you apply to all parts of the experiment (does not change)

Independent variable—variable that you purposely change (what’s being tested)

Dependent variable—variable that is being observed (what’s being measured)

Practice Time!! Identify three possible variables for the

following situations.

2. Determine length of experiment

3. Repeat to verify results

4. Be a good observer

5. Measure exactly

Step 4. Analysis “What happened during the experiment?”

Data is collected and observation are made during the experiment Numerical data—height,

weight, temp… Verbal data—words to

describe observations

Any problems with the experiment are noted along with errors that occurred

Step 5. Conclusion What did I find out?” Scientists will tell what

was learned from the experiment Did the results confirm

hypothesis Did the results deny

hypothesis Are there any more

questions to answer Brief statement that

summarizes the key points and outcomes of the experiment