Notes on the 8 Steps of the Scientific Method also known as Experimental Design The Scientific Method is an organized method of solving problems. It is a step-by step method of inquiry which included both testing and measuring. THE 8 STEPS OF THE SCIENTIFIC METHOD (EXPERIMENTAL DESIGN) I. STATE THE PROBLEM We write a statement that identifies a problem we must solve. A science project (investigation) is not a report nor is it a collection. Naming of the parts or a simple explanation of how or why something works, is not an investigation. A scientific investigation is a step-by-step method of inquiry, which includes both testing and measuring. Choose and state your problem carefully keeping in mind cost, time needed to complete work, and scope of the problem you intend to solve.

Keep the following things in mind when writing a Statement of the Problem: *it is always written as a question *it should be affordable *it is not a report *it must be relatively safe *it is not a collection *it is not a model *you should not use words of opinion *it must include testing and measuring *you must be able to complete it within a month or two Examples: Of the paper towels tested which is the most absorbent? What is the effect of fertilizer on plant growth?

II. HYPOTHESIS We can make an educated guess, a prediction, as to what we think the solution of our problem will be. It is always a statement of what we believe will result from our testing and measuring before proceeding. hy pot he sis Keep the following in mind when you write your hypothesis: *must be written as a complete sentence or sentences *should not begin with “I think” or “I believe” *use key words from the Statement of the Problem in your hypothesis (If the Statement of the Problem is: Will taking vitamin B keep insects from biting you? Then your hypothesis should include the words vitamin B, insects, and bites.) Example: Taking vitamin B will prevent insects from biting you. *must relate to the Statement of the Problem (Thus if the Statement of the Problem is: Which fertilizer will increase plant growth the most? Your hypothesis must deal with fertilizers and plant growth, not the effect of fertilizers on the environment. Example: Of the fertilizers tested, Brand X will increase plant growth the most.

III. OPERATIONAL DEFINITIONS A list of words and their expressed meanings that we will operate under. Check each and every word in the hypothesis and elsewhere, avoid using words of opinion such as: good better bad best worse pretty ugly right wrong yucky There are no specific rules for determining when it is necessary to write an operational definition, however the following clues should help you determine those words that need to be defined operationally: *if there is more than one meaning for the word *if an object is being used differently than it would be in normal circumstances *if an object has been changed in anyway *usually the word from the Statement of the Problem that tells what it is you are measuring needs to be defined operationally

Keep the following in mind when you write an operational definition: *must tell exactly what the word means in this specific investigation *is not the definition from the dictionary *used to define words from your Statement of the Problem, Hypothesis, Materials List, Controls, or Procedures whose meanings may not be clear to the reader *can be used to give the name and address of specific products that are used in the investigation *may be used to describe the specific characteristics of an object that is to be used in the investigation (especially important if you have modified an object for use in the investigation) *should include details of what an object looks like or specifies about how something was determined in the investigation so that everyone is looking for the same thing Example: Consider this case in order to think of a variety of ways that a variable might be operationally defined. You are growing beans in an investigation: you need to operationally define the variable “amount of plant growth.” There are various ways to determine the amount of growth such as: the height of the plant in mm, measured and recorded daily the number of new bean sprouts counted and recorded daily the length of each bean measured in mm and recorded daily

IV. CONTROL We must list all variables (elements that can change or influence the results of our investigation). We must keep our tests and measurements absolutely fair and honest by controlling variables. Some important variables: *time *quantity of materials *quality of materials Independent Variable (also called the Manipulated Variable): In a well-planned experiment, one factor, or variable, is changed at a time. The one variable that is changed is called the independent variable. Dependent Variable (also called the Responding Variable): The variable that is being measured. Constants (also called the Controlled Variables): You must make sure that all the variables are controlled or stay the same except for the independent variable. The variables that stay the same are called constants. Points to consider when writing constants: *ALL variables must be listed *do not list the thing or things that you want to change or test *you only list the variable here you do not state how it will be controlled. You will actually control the variables when you write your: Materials List and Procedures Examples of variables as they should be listed under Controls for an experiment on the absorbency of various paper towels: Independent Variable: brand of paper towels Dependent Variable: amount of liquid absorbed Constants: amount of time that paper towel is submerged in water liquid used to make the spill how much liquid is used to make the spill how you measure to determine how much the paper towel absorbed Control: Many experiments also have a control. A control is an individual instance or experimental subject for which the independent variable is not changed. You can compare the test results to the control results. For example, if you are

V. MATERIALS List completely all materials, item-by-item. This list should include an item number, a brief description, and the quantity or amount to be used. Note that the title for your materials list may need to state how many the materials are intended for: Examples: Materials for each group of 4 students: or Materials for each class of 30: The following should be listed (if appropriate) in this order: *number of items *size of item (separated from the number of items with a dash) *name of container item comes in *brand name (capitalize proper nouns) *specific details *name of object The materials list should be written as a list one item under another. Examples: 1 – 8 oz. bottle Mrs. Stewart’s concentrated liquid bluing 1 – 30 cm Fiskars metric ruler Note that you should use metric units when possible. However since the U.S.A. still uses Standard English Units you may use these units on your materials list since that is how the product is sold in this country.

VI. PROCEDURES Write a complete list of step-by-step sequential directions that you will follow to test your hypothesis. These procedures are to be followed exactly by you (the investigator). It is in this step, as well as in your materials list that you demonstrate how you control the variables identified in step IV. Check to make sure you have done so. Procedures should: *be numbered *written as complete sentences *include specific details *be written in the order that they are to be done *if you are beginning a new step it should be written on a new line Example: 1. Open roll #1 Scott Towels paper towels. 2. Remove 1 or 2 paper towels and label as #1 with a permanent marker. 3. Weigh and prepare 5 grams #1 Scott Towels paper towels. 4. Place 200 mL water into bowl #1 and place it near #1 Scott Towels. VII. OBSERVATIONS List or identify all observations as they occur, or shortly thereafter.

The data should be displayed in a meaningful way, easy to read and interpret. Use graphs, charts, photographs, or other displays that are informative and pleasing to view. *ALL CHARTS AND / OR GRAPHS MUST HAVE A TITLE THAT EXPLAINS ITS PURPOSE *Graphs need to be labeled with an explanation of what the numbers and or words for both the x and y axis mean. *The top of each column and row should be titled. *Do not use abbreviations. *Photographs should have a written description. ***ABSOLUTELY NO INFERENCES***

VIII. CONCLUSION This should be a simple statement that your hypothesis is true, that your hypothesis is not true, or that your work is inconclusive. This conclusion must be backed by your observations in step VII. Example: Of the paper towels tested Scott Brand was the most absorbent.