The Scientific Method/Process Class Notes
Scientific inquiry is a process scientists use to find answers to questions they have about the world around them. They use the steps in the scientific method to design and conduct scientific investigations to explore possible answers. We must learn how to use this process in order to conduct our own investigations through the year.
Steps in the scientific method answer a question.
1. Purpose: What do you want to learn from the experiment?
2. Research: What is already known about the topic?
3. Hypothesis: What do you think will happen in the experiment?
4. Procedure: how will you test the hypothesis and record the results?
5. Conclusion: Do the results support your hypothesis?
Think: Peter Rabbit Hates Peas and Carrots to remember steps in order.
Scientists are problem solvers. They ask many questions about what they see going on in their world. They conduct scientific investigations to find the answers to these questions. Most investigations follow a general pattern.
Choose a topic for investigation: a good topic is one that can be tested with an experiment. It is important that the topic is not too general. Keep in mind a good investigation is one that is: Testable, Repeatable, and Test for Only One Variable. If the topic is based on opinion or personal preferences, then it is not testable.
Stating the Purpose
Scientists explain exactly what they want to learn from their investigation in the purpose. The purpose is written as a question, often called the “Big Question or the Research Question.”
The purpose of an investigation includes three components:
1. It is clearly written
2. It usually starts with the verb “does”, but not always
3. It can be answered by measuring something
Test Yourself
Read each purpose/research question below. If it is testable, circle yes. If it cannot be tested, circle no.
1. Does the amount of fertilizer affect how tall a flower grows? Yes No
2. Are roses prettier than tulips? Yes No
3. How can we make cut flowers stay fresher for a longer period of time? Yes No
4. Can daisies grow in different types of soil? Yes No
5. Do daffodils smell better than carnations? Yes No
Practice writing a purpose for each topic. Record your answers below. Remember to start the purpose with the word “Does.”
Topic / Purpose1. temperature and bread mold
2. texture of paper towels
3. colored light and plant growth
4. light and the activity of meal worms
5. Rust and the strength of magnets
After choosing a topic to investigate and writing a testable research question (purpose), its time to find information about your topic. However, some topics are very broad. You must narrow your topic enough to focus on the most important parts relating to your experiment and research only those parts.
The most important parts of your experiment are the variables. When conducting a test, scientists, change certain “things” and then observe how they affect the experiment. These “things” are called variables. The Variables are all the factors that can change in an experiment, possibly affecting the results. Variables in an experiment are often referred to as factors, traits, or conditions. It is important that you test only one variable at a time; this way, you can be sure it’s the one thing that caused the results.
In any scientific investigation, there are three kinds of variables:
1. The Independent (or manipulated) Variable is the ONE factor or condition that is intentionally changed by the experimenter.
2. The Dependent (or responding) Variable is the factor or condition that may be affected as a result of changing the independent variable. The dependent variable is what you measure or observe to obtain your results.
3. The Constant Variables are all the factors or conditions that must be kept the same in an experiment.
For example, imagine that you are investigating this research question: Will M&M color dissolve faster in water or in another clear liquid? The three types of variables in the experiment are identified below:
Independent Variable (IV): Type of clear liquid (intentionally changing)
Dependent Variable (DV): Time it takes for color to dissolve (measuring time)
Constant Variables (CV): color of M&M, amount of liquid, type of M&M (plain or peanut), time at which M&Ms are dropped into liquid, etc.
Practice
Read each question below. Identify the IV, DV, and CV of each experiment.
1. Does the amount of sunlight affect pea plant growth?
IV:______DV:______
CV:______
2. Which type of soda has more sugar: Brand X, Brand Y, or Brand Z?
IV:______DV:______
CV:______
3. Is the height of a ball’s bounce affect by the height from which the ball is dropped?
IV:______DV:______
CV:______
4. Which battery will last the longest? Superlast or Energy Star?
IV:______DV:______
CV:______
(Homework assignment, page 4 “Mastering the Scientific Method”)
Form a Hypothesis
After completing the research, a scientist is able to make an educated guess or prediction about what will happen in the experiment. This prediction is called the hypothesis. A clearly written hypothesis follows a set pattern. It answers the question stated in the purpose. It is brief and to the point. It uses the same word pattern as the purpose.
Example
Purpose: Does the depth of a seed affect its sprouting time?
Hypothesis: An increase of the depth of a seed will increase its sprouting time.
(Lab~ Form a hypothesis, page 5)
Practice. Write a hypothesis for each purpose.
1. Purpose: Does fertilizer affect the growth rate of a plant?
Hypothesis:______
2. Purpose: Does air pressure affect the height a basketball will bounce?
Hypothesis:______
3. Purpose: Does age affect the heart rate of humans?
Hypothesis:______
Procedure
The procedure is a step-by-step set of directions for testing the hypothesis. A good procedure is so detailed and complete that other scientists can duplicate the experiment. The procedure includes several components.
Materials: Materials are a list of items needed to conduct the experiment. The list is written similar to a recipe. Materials and supplies are listed in the order they are to be used in the experiment.
Experiment: The experiment is a test designed to answer the question stated in the purpose. The test consists of two groups:
o Experimental Group: This group includes the part or parts of the experiment that are changed and tested. The results are then compared to the control group to determine what changes have taken place.
o Control Group: This group includes the part or parts of the experiment that are left unchanged. The conditions a scientist wants to remain the same during the experiment are called constants.
Observe, Record, & Analyze the Data
While conducting your experiment, it is very important to make clear and accurate observations. An observation involves using all five senses to make sense of the world around you. Scientists use observations to gather data that will support or disprove their hypothesis.
There are two basic types of observations:
1. Quantitative Observations are observations that involve a number in the form of an amount or measurement. Noticing that there are 12 students working in the library is a quantitative observation. Scientists try to use quantitative observations as much as possible because they are more accurate and precise.
2. Qualitative Observations are observations that use non-numerical descriptions. Noticing that your friend’s sweater is blue and green is a qualitative observation.
Observe the classroom around you. Make five quantitative and five qualitative observations about the classroom. Write them in the chart below.
Quantitative Observations / Qualitative Observations1. / 1.
2. / 2.
3. / 3.
4. / 4.
5. / 5.
Scientific observations need to be recorded in an organized way so the experimenter can analyze the information. All experiments produce data, which are facts, figures, and other evidence gathered through observations. Making sense of the data is called data interpretation.
(Graphing Skills p. 19 TF & p. 10 SMI)
Drawing Conclusions
The final step in the scientific process is to draw conclusions. A conclusion is a summary of what you have learned from the experiment. When reaching conclusions, you should decide whether the data you collected supports your hypothesis or not. It is also important to consider if you have collected enough data or if more testing needs to occur before a conclusion can be reached. Examining the process you used and deciding if there were any unidentified or unexpected variables that could have affected the results is also necessary when drawing conclusions. Remember, it is not a problem if the experiment does not turn out how you expected or does not support your hypothesis. Conclusions often lead to new scientific questions and experiments!
(Practice MSM, p. 14)
J. McNulty 7th Grade Science 2010-11