7 Steps of the Scientific Method 3. Formulate a Hypothesis: Predict a possible answer to the problem or question.A hypothesis is a testable explanation for a question!
8 Steps of the Scientific Method Experiment: a planned procedure to test a hypothesisAn experiment must include a procedure to follow.Includes a detailed materials list.The outcome must be measurable.
9 The control group may be considered as a “no treatment” group is the group in an experiment that serves as the standard of comparison.The control group may be considered as a “no treatment” group
10 Control Group continued All experiments must have a control group.
11 Experimental (Test) Group The group in an experiment that receives experimental treatment.The independent variable is in the test group.
12 Independent VariableThe independent variable is the ONE factor that’s intentionally changed by the experimenter in the experiment.
13 Dependent Variablethe factor in an experiment that is measured. It may change as a result of changes made in the independent variable.
14 Steps of the Scientific Method 5. Collect and Analyze Results:Include tables, graphs, and photographs.
15 Types of Data Quantitative data = numerical data Qualitative data = descriptive data
16 Steps of the Scientific Method 6. Conclusion: An evaluation of the hypothesis based on the results.Make recommendations for further study and possible improvements to the procedure.
17 When the experiment is complete, you will need to - Communicate the Results: Lab writeups, published articles, presentations.Why is this a good idea?
18 REPEAT – REPEAT - REPEAT In order to become generally accepted, the experiment has to be repeated many times by many different people.REPEAT – REPEAT – REPEATAn experiment MUST be able to BE REPEATED. If it CANNOT be repeated, the results are not valid.
19 Scientific TheoryA theory is a set of related hypotheses that have been tested and confirmed many times by scientists.A theory unites and explains a broad range of observations. It is subject to change as new evidence becomes available
20 Scientific LawAn observation or description that is consistently/always true under certain circumstances. Laws do not explain WHY something happens (theories do that)
21 Let’s put our knowledge of the Scientific Method to a realistic example that includes some of the terms you need to use and understand.
22 She explains that yeast releases a gas as it feeds on sugar. Problem/QuestionJohn watches his grandmother bake bread. He ask his grandmother what makes the bread rise.She explains that yeast releases a gas as it feeds on sugar.
23 Problem/QuestionJohn wonders if the amount of sugar used in the recipe will affect the size of the bread loaf?
24 Caution! Be careful how you use effect and affect. Effect is usually a noun and affect, a verb.“ The effect of sugar amounts on the rising of bread.”“How does sugar affect the rising of bread?”
25 Observation/Research John researches the areas of baking and fermentation and tries to come up with a way to test his question.
26 Formulate a Hypothesis John then comes up with a hypothesis.“If more sugar is added, then the bread will rise higher.”
27 HypothesisNotice that his hypothesis is testable. He can design an experiment to answer this question.
28 ExperimentJohn sets up his experiment with a control group, test group, independent variable and dependent variable.
29 What are the independent and dependent variables?
30 VariablesIndependent variable = amount of sugar. John is going to use 25g, 50g, 100g, 250g and 500g of sugar in his experiment.Dependent variable = size of the bread
31 Control and Test Groups What are the control group and the test group?
32 Control GroupBecause his grandmother always used 50g. of sugar in her recipe, John is going to use that amount in his control group.
33 Test GroupJohn decides to test 4 other amounts of sugar, so he has 4 test groups.
34 ConstantsJohn keeps all other factors the same so that any observed changes in the bread can be attributed to the variation in the amount of sugar.
35 ConstantsThe constants in an experiment are all the factors that the experimenter attempts to keep the same.
36 Can you think of some constants for this experiment?
37 Constants They might include: Other ingredients to the bread recipe, oven used, rise time, brand of ingredients, cooking time, type of pan used, air temperature and humidity where the bread was rising, oven temperature, age of the yeast…
38 John is going to test each sugar variable 3 times. TrialsTrials refer to groups that are exposed to the same conditions in an experiment.John is going to test each sugar variable 3 times.
39 Collect and Analyze Results John comes up with a table he can use to record his data.John gets all his materials together and carries out his experiment.
40 Size of Baked Bread (LxWxH) cm3 Size of Bread Loaf (cm3)TrialsAmt. of Sugar (g.)123AverageSize (cm3)257687447617585012961188126010010801116250672576588612500432504360Control group
41 Collect and Analyze Results John examines his data and notices that his control worked the best in this experiment, but not significantly better than 100g. of sugar.
42 ConclusionJohn rejects his hypothesis, but decides to re-test using sugar amounts between 50g. and 100g.
43 Once again, John gathers his materials and carries out his experiment. Here are the results.
44 Can you tell which group produced the largest loaf of bread?
45 Size of Baked Bread (LxWxH) cm3 Size of Bread Loaf (cm3)TrialsAmt. of Sugar (g.)123AverageSize (cm3)5012961440134460140413807016381560161280133290108012009721084Control group
46 Conclusion John finds that 70g. of sugar produces the largest loaf. His hypothesis is accepted.
47 Communicate the Results John tells his grandmother about his findings and prepares to present his project in Science class.
48 Other things to consider… Ethics – study of what is right & wrong.…because it CAN be done, does that mean it SHOULD be done?…can you think of any ethical situations related to biology?Technology – application of science for practical purposes… as opposed to pure science, which is studying science just for the sake of gathering knowledge … may or may not have a practical application