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The Scientific Method Experimental Design Laboratory Safety & Equipment X Chemisty Unit I.

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Presentation on theme: "The Scientific Method Experimental Design Laboratory Safety & Equipment X Chemisty Unit I."— Presentation transcript:

1 The Scientific Method Experimental Design Laboratory Safety & Equipment X Chemisty Unit I

2 What is Chemistry?? In your own words, please write down how you would define the following words: Biology vs. Chemistry vs. Physics

3 What is Chemistry?? Biology The study of living organisms Physics The study of forces and motion Chemistry The study of matter and its reactions and properties

4 The Scientific Method A Way to Solve a Problem

5 What is the Scientific Method? The steps someone takes to –identify a question –develop a hypothesis –design and carry out steps to test the hypothesis –document observations and findings to share with someone else. In other words… it’s a way to solve a problem.

6 The steps of the Scientific Method are: State The Problem Gather Information Form a Hypothesis Test The Hypothesis Collect and Analyze Data Conclusion

7 Scientists have to take the time to think logically when they are investigating a question or problem. They break things down into many steps that make sense.

8 Scientists develop a question, gather information, and form an hypothesis.

9 The next step scientists take is to create and conduct an experiment to test their hypothesis.

10 A key to experiments is observing what happens and writing it down. Gathering information or data and documenting it so it is readable and makes sense to others is very important.

11 Once a scientist completes an experiment, they often repeat it to see if they get the same findings and results. This is really what we call verification, or checking things out to make sure everything was valid and will happen again and again.

12 Scientists share their experiments and findings with others. Because they share their experiments and findings, scientists can learn from each other and often use someone else’s experiences to help them with what they are studying or doing.

13 The steps of the Scientific Method are: State The Problem (Ask a Question) Gather Background Information Form a Hypothesis Test Hypothesis (Perform Experiment) Collect and Analyze Data Draw Conclusions

14 If the Hypothesis is supported then the experiment is repeated several times to verify the results. If the hypothesis is not supported then the hypothesis is modified and a new test of the hypothesis is performed. What Next?

15 Scientific Method in Action The Strange Case of BeriBeri 1. State the Problem 2. What was the hypothesis? 3. How was the hypothesis tested? 4. Should the hypothesis be supported or rejected based on the experiment? 5. What should be the new hypothesis?

16 Scientific Method in Action How Penicillin was Discovered 6. Identify the problem. 7. What was Fleming's hypothesis? 8. How was the hypothesis tested? 9. Should the hypothesis be supported or rejected based on the experiment?

17 Apply the steps of the scientific method to each step of the following example: A.Jenny determines that her homemade solution was just as effective as the store-bought pesticides B.Jenny states that if she sprays her vegetables with a natural, homemade solution to help fight the bug problem, then her vegetables will still grow to the same size as they would if she used store bought pesticides C.Jenny goes to the library and looks up different kind of pesticides and their effect on vegetables and also looks up natural remedies to help solve her bug problem D.Jenny sprays one third of her vegetables with store bought pesticides, one third with her homemade solution, and does not spray the remaining third (her control group) E.Jenny wonders how she can protect her plants from bugs without harming the vegetables F.After one week, Jenny compares and tests the differences in her vegetables

18 Experimental Design Your guide to getting results

19 Every Experiment has two parts: The Control Group –This set-up is the standard by which the test results can be compared –This group contains the population where nothing was changed The Experimental Group –One factor is changed between the control group and experimental group –The changes found in this set- up are usually due to the variable (the factor that was changed)

20 The Variable is something that can be changed between the control group and the experimental group. It is the goal of an experiment to determine the effect the variable has on what is being tested There are usually two variables when an experiment is performed: The Dependent Variable & The Independent Variable

21 The Dependent Variable is the factor that changes as a result of changes in the independent variable. –It DEPENDS on the other variables!! The Independent Variable is the factor that, as it changes, affects the measure of another variable. –You (as the experimenter) set the independent variable.

22 Identify the Independent & Dependent Variable A group of college students were given a short course in speed- reading. The instructor was curious if a monetary incentive would influence performance on a reading test taken at the end of the course. Half of the students were offered $15 for obtaining an A or B on the test; the other half were not offered money. Independent variable: Dependent variable: Experimental group: Control group:

23 Lets take a look at an example Let’s say I am from Mars and have never seen the leaves change color. I decide to perform an experiment to find out why they change color.

24 My Hypothesis Since the leaves change colors in the Fall and since it gets cold in the Fall, I believe that the leaves change color due to the drop in temperature.

25 My Set Ups (Groups) I went to Waterloo Gardens intent on finding two identical Maple Trees. I found two that were about the same height, had about the same number of leaves, were in the same type of soil, and were in the same amount of soil.

26 When I get home I... Placed one of the trees in a closet with a lamp that was on a timer so the tree would receive 12 hours of light each day I placed the other tree in a different closet that was the same size and that received the same amount of light (12 hours)

27 After some research… I found that the average summer time temperature was 85 degrees and set a heater and a thermostat into one of the rooms to simulate summer time. I also found that the average temperature in the winter was 42 degrees and set a cooler and a thermostat into the other room to simulate winter time.

28 While conducting the experiment I…. Gave each plant the same amount of water at the same time each day Applied the same amount of fertilizer on each tree Kept a neat and detailed data log on each plant that kept track of the %-age of green leaves.

29 This was my data table:

30 While analyzing, it is often a good idea to create a graph from data. A graph gives us a visual representation of our data. By looking at a graph, trends and relationships can often be seen.

31 Conclusion… After analyzing my data, was I was able to conclude that temperature was the cause of leaves changing color in the fall?

32 In the space in your notes can you... Identify the variables in the experiment –Which ones did I keep the same in each experiment? –Which ones did I change in each experiment? Identify the independent variable? Identify the dependent variable? Identify the control set up (group)? Identify the experimental set up (group)?


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