In science, a lot of investigation is needed to prove scientific theories and laws. Scientists use a method, called the scientific method
to test and retest information. Depending on which source you use, you will notice that there a different number of steps listed.
The method itself is the same, some just list a few less steps. This tutorial uses 7 steps. The acronym for remembering these steps in order
is I C STARS
Step 1: Identify the Problem
Before you solve a problem you have to have an identifiable problem. So let's create one! Always write out your problem in question form.
Heidi wants to design an experiment about how much watering a plant affects plant growth.
Problem: Does the amount of water affect the growth of bean seeds?
Step 2: Collect Information About the Problem
Collecting information about a problem depends on whether you have basic knowledge about the problem you or trying to solve or not. In this
case it may be useful to look up information related to plants and the environment. Looking at other research can help you make some decisions
Step 3: State Your Hypothesis About the Problem
Using an if-then statement helps to keep the hypothesis specific. The hypothesis also has to be testable. And most important, it has to relate to
Hypothesis: If I water my plants too little, then they will not grow very much.
Step 4: Test the Hypothesis
DESIGN THE EXPERIMENT
In order to test this hypothesis, we need to design an experiment that controls certain variables.
This makes it easier to identify the independent and
We need a list of materials that will be used to test this hypothesis and the describe the environment where
the testing will take place.
Below is the experimental design setup to test Heidi's hypothesis about bean seed growth and watering.
15 1 cup pots containing same type of soil
15 identical bean seeds (same kind of bean)
Plant each seed 1 inch below the soil surface
Place all of the pots in a controlled location to ensure that they
the same amount of the following:
airflow (could affect moisture)
These are the controlled variables
The 15 pots will be divided into 5 sets of 3 pots.
Each set will receive a different amount of water daily.
This is the independent variable (the one you change)
The amount of water will be the independent variable
The amount of growth will be the dependent variable
Observe daily for 2 weeks
Step 5 & 6 Analyze and Record Results
These two steps are often done at the same time.
While you are making observations daily, you
should be recording the information in a way that it can be organized
in a data table for analyzing later. Pictures, graphs and
charts are ways to present your data for interpretation.
To the right are examples of a
data chart and a
Step 7 Draw Conclusion about the Test Results
Based on the results of your test, does your conclusion support your hypothesis? If not, you might adjust a couple of things.
You may change your hypothesis or make it more specific. You can run the test on the hypothesis again for validity. Or you could
re-analyze your data to see if you overlooked something. All of these suggestions are useful, but may not all be used.