1. EXPERIMENTAL DESIGN … AND HOW TO WRITE UP A LAB IN 8 TH GRADE SCIENCE …

2. The PROBLEM Developed as scientists hypothesize and research … A QUESTION that shares the variables that will be studied in the experiment. In science class … I provide the problem that addresses a topic we are studying.

3. Examples of problems … How does temperature affect melting rate? How does chair color affect seat choice? How does density affect solubility?

4. Writing the Title … The title is a formal title … The effect of _______ on ________. Fill in independent variable here!!!! Fill in dependent variable here!!!!

5. Title Examples How does temperature affect melting rate? The effect of temperature on melting rate How does chair color affect seat choice? The effect of chair color on seat choice How does density affect solubility? The effect of density on solubility

6. Independent Variable The variable that we change on purpose. What the experiment is testing … The variable that is being manipulated Always comes first in the data chart and is the foundation of every graph (x axis)

7. Independent Variable Examples … How does temperature affect melting rate? How does chair color affect seat choice? How does density affect solubility? Ask yourself … what am I testing? What will I change on purpose?

8. Dependent Variable The part of the problem that I am trying to find out. I measure it and write it in the data chart as I perform the experiment The variable that is measured or is the responding to the change(responding variable) Always comes last in the data chart and is the side of the graph (y axis)

9. Dependent Variable Examples How does temperature affect melting rate? How does chair color affect seat choice? How does density affect solubility? Ask yourself … what am I measuring? What am I trying to find out?

10. Constants Watch Mr. Edmonds Variable Song on Youtube. They are kept the SAME in experiments. They PROTECT the VALIDITY of the experiment by keeping everything surrounding the IV and the DV the same. They keep outside factors from affecting the experiment. They make sure the changes in the IV are really making the DV do what it does.

11. Constant Examples How does temperature affect melting rate? Substance that is being melted, shape of what is being melted, how heat is added How does chair color affect seat choice? Chair style, location of the chairs, condition of the chairs, people near the chairs How does density affect solubility? The temperature of the solvent, whether the substance that is being dissolved is crushed up or chunky, what the solvent is

12. Introduction This should be two or three sentences that PROCEDURES the lab in your own words. Listen to my directions and hints … write down in your own words how to perform the lab.

13. Hypothesis An educated prediction about how the experiment will turn out … Always written in the following format … NO “I Thinks.” If ____________, then ______________. Fill in independent variable info here!!!! Fill in dependent variable info here!!!!

14. Hypothesis Examples How does temperature affect melting rate? If the temperature increases, the melting rate will also increase. How does chair color affect seat choice? If the chair color is dark like blue or black, more people will choose them. How does density affect solubility? If the density is a lower number, then it will dissolve more easily.

15. The Control NOT THE SAME AS THE CONSTANT!!!!!! You use the control to COMPARE all of your collected data to a starting place.

16. IV’s and DV’s in Data Charts and Graphs Independent Variable Dependent Variable Always comes first in the data chart !!! Always comes last in the data chart!!! Independent Variable Dependent Variable Y axis X axis Data Chart Graph

17. Control Examples How does temperature affect melting rate? Control could be 0 because that could be a starting place … or you could pick room temperature as your starting place. How does chair color affect seat choice? Control can’t be zero … it has to be a color. You could research the most popular chair color and start with it. How does density affect solubility? Density has to have a value so zero does not work … You could start with an easy number to work with like 1 …

18. Collecting Data … Repeated Trials Repeated Trials make data more valid or true!! You try each level of the IV several times to make sure you minimize or hide the errors that you make. IV DV Trial OneTrial TwoTrial ThreeAverage of Trials

19. What kind of data are you collecting? Qualitative or Quantitative??? How do you decide … Look at the DV to decide. If the DV is numbers when you write it in the data chart, it is QUANTITATIVE! If the DV is descriptions, pictures or words when you write it in the data chart; it is QUALITATIVE!

20. Qualitative v. Quantitative?? QUALITATIVE QUANTITATIVE L is for letters that make words and descriptions!! N is for numbers when you measure or count!

21. Examples of Qualitative and Quantitative Data How does temperature affect melting rate? Melting rate is the DV, and it will be numbers because rate is speed … QUANTITATIVE How does chair color affect seat choice? Seat choice will be a description of some type … QUALITATIVE How does density affect solubility? SOLUBILITY could be either a description or a measured amount of how much is dissolved … so more information about the experiment set up would be needed to decide between Qualitative and Quantitative data.

22. Graphing the data … Bar or Line? You look at the IV to make this decision … If the IV is numbers when it is written in the data chart, make a LINE GRAPH. If the IV is words or pictures when it is written in the data chart, make a BAR GRAPH. Watch Brainpop on Graphs.

23. The Conclusion There are three Questions to answer … Each Question should be answered in at least 4 sentences.

24. Question One … 1.What happened in the experiment? Talk about the data that you collected. Do you see any patterns? DO NOT TRY TO EXPLAIN WHY!! This should be a very factual paragraph … it should only address what anyone could see if they looked over your data.

25. Question One Example How does temperature affect melting rate? In this lab there were three patterns that I observed in the data. First, I saw that as my Independent variable, temperature, got higher; my dependent variable, melting rate, got faster for most of the experiment. Second, once my temperature reached 30 degrees Celsius; my melting rates stayed very close to the same for the rest of the experiment. Finally, my graph shows a strong positive trend at first then levels off at 30 degrees Celsius.

26. Question Two Do you accept or reject your hypothesis? Why do you think the data turned out the way that it did? What caused the patterns or trends that you see in your data? Try to explain WHY!! Use the science that we are studying … past experiences … or science from the past to help you explain your data.

27. Question Two Example How does temperature affect melting rate? After looking over my data, I believe the trends that I observed can be explained by two things. First, heat always makes things melt faster. Second, once you reach a certain temperature; the differences in melting rate will be hard to observe in a classroom because the equipment is not sensitive enough. My graph clearly agrees with these assumptions.

28. Question Three What errors affected your data? Look at the constants that you planned to keep the same … how well did you do? Were there things that happened that may have messed up your data? Find at least three errors that affected your data.

29. Question Three Example How does temperature affect melting rate? There were three noticeable errors that affected my data in this experiment. First, the heat source, the candle, was hard to work with. It did not apply heat evenly. Second, as the experiment continued; we were not as careful to always start with the same size ice cube. This made our data a little less accurate. Third, as the experiment continued; we worked so quickly that the pie pan that held the ice cube stayed warm between trials. This made our data less reliable.

30. Make sure you have the following: Problem: In the form of a question Independent Variable: what is being tested or changed on purpose Dependent Variable: what is being measured or observed Constants (at least 3): stay the same to protect the IV and DV Control: Tell what will be used as the starting place/point of comparison for the experiment. Introduction: Procedure/steps of the lab directions /2 or 3 sentences Title: The effect of IV on DV Hypothesis: If IV, then DV. Data Chart: IV on the left and DV on the right/Include Repeated Trials Graph: IV on the X axis, and DV on the Y axis/Bar if IV is words or pictures, and Line if IV is numbers/Graph only the average of the trials. Conclusion: Answer all three questions with at least 4 sentences.

31. Problem: Title: Independent Variable: Dependent Variable: Constants (at least 3): Control: Hypothesis: Introduction Data Chart: Graph Conclusion: