Scientific Method

Big Ideas Define Scientific Method. Learn why Scientific Method is used in the science

and engineering jobs. Review and understand the individual steps of

Scientific Method. Learn about independent and dependent

variables.

What is Scientific Method Scientific Method is the procedure that is used to gain

understanding about natural science.• Scientific Method uses a specific process to organize

thoughts and activities in a consistent, logical manner.• The result of scientific method are conclusions that

become scientific explanations.

Scientific Method is used because…• Using the process ensures scientists/engineers think

through all aspects of the activity.• With everyone using the same process, working together

is easier.• Used since the 17th Century…It works!!

Scientific Method Steps There are six basic steps to scientific method.

• Purpose/Question – Decide what topic to learn about?• Research – Investigate the topic.• Hypothesis – Predict what will happen.• Experiment – Test the hypothesis.• Analysis – Record results of the Experiment.• Conclusion – Explain the results.

Sometimes research is omitted from scientific method steps If the topic is very new, sometimes no research exists.

Sometimes individuals will slightly modify the basic steps and rename the procedure…However the basics steps are still the same.

Purpose/Question First step is to define the question or define the purpose

for scientific method activity.

The basis for question can come from…• Observation – process of obtaining information by

using our senses.• Reading a scientific text or report.• Boss or teacher

The question needs to be well-defined or clearly stated so that it can be investigated.• Example observation: Some tomato plants in my

garden grow taller than others.• Example question: Why is there a difference in

height between my tomato plants?

Research Second step is to perform research on the question that is being

asked. • This helps us understand what other people have already

learned about our question.• Having more information help us create a better hypothesis

(next step).

Where can research be found?• Internet (reputable sources only)• Peer reviewed scientific articles• Cited sources• Textbooks• Expert individuals• Not wikipedia

Research Example research: What sources could we use to better

understand the growth of tomato plans?

Potential Resources:• Gardening book• Internet search• Person – Employee at a nursery, Mom

Some factors that impact tomato plant growth are…• Amount of sunlight• Amount of water• Quality of soil – nutrients/rockiness/other• Plant disease• Insects• Maybe others…

Hypothesis Third step is write a hypothesis. Hypothesis is a

statement that is a testable explanation that leads to investigation.• Educated guess based…and could be wrong.• Must be written so that a test/experiment can be

made to test the hypothesis.• Written as a statement – not as a question.

Example hypothesis: If the tomato plants receive the correct amount of water, then plant grow larger.

Experiment Fourth step is to conduct an experiment. Experiment is an

organized procedure to study a topic under controlled conditions• Actions that will test if the hypothesis is correct.• Requires planning to ensure the hypothesis is actually

tested correctly.• Experimental procedure needs developed. This is

important in case the experiment is repeated.• Appropriate equipment is required…both for carrying out

the experiment and any potential measurements.• Data is information gathered by observation or

experimentation. Collecting data is the main purpose of the experiment.

Experiment Example experiment:

• Plant 9 tomato plants in 9 identical containers.• Each plant will have the same soil.• Each plant will receive the same sunlight.• None of the plants will receive any pesticides.

• Plant will receive different watering conditions to test the hypothesis. Group 1 will be 3 plants that receive 1 quart of water per day. Group 2 will be 3 plants that receive 2 quarts of water per day. Group 3 will be 3 plants that receive 3 quarts of water per day.

Experiment Example experiment (con’t):

• Plant height will be measured at the beginning of the experiment.

• Experiment will be done for 21 days.• Plant height will be measured at the end of 21 days.• The change in height of the plants will be the final data.

In experimental design, it is usually preferred to have more than 1 trial.• In our example, not all tomato plants are the same…so having

three plants hopefully gives a result that represents an average tomato plant.

Experiment When designing experiments, collecting data and showing

results, it is important to understand dependent and independent variables.• Independent variable is a variable that is changed

deliberately as part of the experiment.• Dependent variable is a variable that is impacted by

changing an independent variable.

What are the independent and dependent variables for the tomato plan experiment?• Independent variable = water amount• Dependent variable = change in height

Analysis Analysis is the fifth step in scientific method.

For analysis, records are made of what happened during the experiment.• Observations through our senses.• Measurements with equipment.• Separate by independent variables.

Also as part of analysis, scientists and engineers often take numerical data and summarize in graphical form.• Data is often much easier to understand

when presented as a picture. (Picture is worth 1000 words.)

• Type of analysis used depends on type of data collected.

Analysis

Group Plant StartingHeight

EndingHeight

Change in

Height

Group 1 - 1 quart of water per day

1 3.4 8.3 4.92 3.0 7.6 4.63 3.1 7.9 4.8

Group 1 - 2 quarts of water per day

1 3.2 9.3 6.12 2.9 9.8 6.93 3.3 9.9 6.6

Group 3 - 3 quarts of water per day

1 3.0 6.6 3.62 3.1 6.3 3.23 3.1 6.4 3.3

Example analysis:

Often, it helps to put numerical results into a visual chart.

Conclusion Forming conclusions are the sixth and final step in using

scientific method. Purpose of the conclusions is to provide a final explanation for the results.

The conclusion is intended to…• Show the journey from start to finish.• Share the new understanding gain from the work.• Possibly show real life examples as part of a presentation.

There are several ways that information is shared.• Science journals• Magazine articles• Live presentations• Science fair or homework assignment

Conclusion Example conclusion:

• The hypothesis is confirmed. • There is an optimum amount of water that allows

tomato plants to grow at a maximum rate.• Too little water resulted in a lower amount of plant

growth.• Too much water also resulted in the least amount of

plant growth.

Quick Review What is scientific method? Why do scientists and engineers use scientific method? Name the six basic steps involved in scientific method. What is an observation? What is a hypothesis? Explain why performing research helps individuals create a better

hypothesis? Why are experiments done? Explain what data is? Describe the difference between an independent and a dependent

variable. Explain what is done for analysis? Why do scientists and engineers often put their results into a

graph? Why is the conclusion done?