Unit 1 - 8th Grade Science Experimental Design The SCIENTIFIC METHOD It’s how we do things around here! I can name (in order), describe, and give examples of the steps of the Scientific Method. The Scientific Method - Definition - A process of research in which a series of steps are used by to answer questions and solve problems. The Scientific Method: There are many diļ¬erent versions of the Scientific Method. Some are VERY simple like the first ones you learned and some are more complex such as those used by practicing research scientists. Regardless of the number of steps identified, the process is STILL, and ALWAYS the same We will focus on a FIVE STEP version. STEP 1: State the PROBLEM STEP 2: Form a HYPOTHESIS STEP 3: EXPERIMENT STEP 4: RECORD & ANALYZE data STEP 5: Draw CONCLUSIONS STEP 1: State the PROBLEM * In this step, you figure out that there is a problem in need of a solution. * What is it you’re curious about? * What is it you want to test? * The problem that needs to be solved must be clearly stated. Think about examples in you OWN life! STEP 1: State the PROBLEM EXAMPLE: I’m constantly having to replace goldfish because they’re always dying. STEP 2: Form a HYPOTHESIS * This is an “Educated Guess” of what you expect the outcome or the solution to the problem to be. What do you think will happen if...... * Often times it is an “If.....then” statement. * “If I slam the door, then students will jump.” STEP 2: Form a HYPOTHESIS EXAMPLE: If I remove the chlorine from the water before placing the fish in the bowl, then the fish will live longer. STEP 3: EXPERIMENT * How will you test your hypothesis to see if it is correct, incorrect, or inconclusive? * This part has to be very detailed, explaining exactly how you will test your hypothesis. The idea is that someone else should be able to read your experiment and duplicate it EXACTLY. STEP 3: EXPERIMENT - continued A CONTROLLED experiment tests only ONE factor at a time. Otherwise you wouldn’t know what caused the results. It will have a CONTROL GROUP and one or more EXPERIMENTAL groups. A CONTROL Group is a standard used for comparison later. (The Control is NOT tested.) The Experimental groups gets the “test”. All the factors for the CONTROL and the EXPERIMENTAL groups are the same EXCEPT for one factor, which is called the INDEPENDENT VARIABLE. STEP 3: EXPERIMENT - continued An INDEPENDENT VARIABLE is the one thing you CHANGE in your experiment. (Independent = Alone) A DEPENDENT VARIABlE is the result of the independent variable that you will observe or measure...THE CHANGE you’re looking for. (The DEPENDENT VARIABLE “DEPENDS” on the Independent Variable.) CONSTANTS are EVERYTHING else you must keep exactly the same between groups. Remember, you only change the independent variable. All else remains the same. STEP 3: EXPERIMENT Example: I’ll buy “Chlorine Remover” from the pet store. I’ll then buy four new goldfish, out of the same tank at the store. They should be equal sizes and equal “health”. I’ll prepare two bowls, one with straight tap water, the other with tap water treated with “Chorine Remover” following the directions. I’ll place two fish in one treated bowl and the other two in the second bowl. STEP 3: EXPERIMENT Example Continued: I’ll be sure the water temperature is the same, the location of the bowls is the same, and that all fish are fed equal amounts. I’ll monitor the health of the fish hourly and record my observations. STEP 4: RECORD & ANALYZE data * Record and examine the results of your experiment. Your “data” could be simple observations you’ve written down in a science class, to hundreds of pages gathered over years of experimenting for those who may be trying to find a cure for cancer. * Look to see what the data from your experiment tells you about your hypothesis. HOUR 1 2 3 4 5 6 7 8 9 10 11 12 13 Bowl 1 Experimental Group Bowl 2 Control Group Fish swimming excitedly Fish swimming excitedly Fish swimming normally Fish swimming excitedly Fish swimming normally Fish swimming excitedly Both fish swimming normally Fish swimming excitedly Both fish swimming normally Fish swimming excitedly Both fish swimming normally Fish swimming excitedly Both fish swimming normally Fish movement slowed Both fish swimming normally Both fish barely moving Both fish swimming normally Both fish barely moving Both fish swimming normally One fish dead, other barely moving Both fish swimming normally One fish dead, other barely moving Both fish swimming normally Both Fish Dead Both fish swimming normally Both Fish Dead STEP 4: RECORD & ANALYZE DATA EXAMPLE: Each hour I recorded the activity of the fish, with small notes, in a data table I created. (If they were swimming normally, quickly, slowly, near the bottom, near the top, and if they went belly-up) In looking at the data table, it appears fish in the untreated bowl started swimming nervously within the hour and continued to do so for the next 6 hours. After 6 hours, their swimming slowed to near nothing. The first fish was dead at hour #10, the second died at hour #12. 24 hours later, the fish in the treated bowl are still swimming and appear normal. STEP 5: Draw CONCLUSIONS Based on your data/the results of your experiment, was your hypothesis CORRECT, INCORRECT, or INCONCLUSIVE? How could your experiment have been more valid? Is the data you gathered reliable? What mistakes may you have made? Share your results with others. STEP 5: Draw CONCLUSIONS Example: Based on the observation data recorded, my hypothesis appears to correct. The fish in the untreated bowl died quicker while those in bowl treated with the chlorine remover lived longer. I could make this experiment better by using more bowls and more fish. Scientific Method Example Analysis: INDEPENDENT VARIABLE: Chlorine remover used DEPENDENT VARIABLE: The health of the fish CONTROL (GROUP): The fish that didn’t get their chlorine removed. EXPERIMENTAL GROUP: Fish that did get the chlorine removed. CONSTANTS: Same type of fish, from the same store tank, same size, same health, water from the same source, same temperatures, same type/size of bowls, same location for bowls, same treatment of all fish How can I remember the steps in order? How about an acronym? State the PROBLEM P Form a HYPOTHESIS H EXPERIMENT E RECORD & ANALYZE DATA D Draw CONCLUSIONS C Such as: Penguins hungrily eat delicious crabs! NOW, STUDY THESE NOTES and EXAMPLES! Soon, you’ll design your OWN Experiment. In it, you’ll need to correctly follow the Scientific Method.
