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1 Scientific Method
2 1. Observation Leads to collecting data Data: The information collected from an experiment.
3 Asking a Question Based on observations; one or more questions are generated
4 2. Hypothesis hypo (less than) thesis (theory) Explanation for what you have seen and recorded An educated guess? A question or statement that can be tested. A suggested answer to a well-defined scientific question - ( an explanation on trial)
5 Forming a Hypothesis Statement is testable if evidence can be collected that either does or doesn’t support it It can never be proven beyond doubt Often must be refined and revised or discarded
6 Predicting To test hypothesis it is necessary to make predictions that logically follows from the hypothesis A statement made in advance that states the results that will be obtained from testing the hypothesis Often in the form of an “if-then” statement
7 3. Experiment A procedure to test a hypothesis, under controlled conditions – conducting a controlled experiment.
8 3 Kinds of Variables Controlled Variable – a variable that is not changed Also called constants Allow for a “fair test” Controls ensure that all variables in the experiment are the same except for the variable being tested.
9 3 Kinds of Variables DRY MIX Independent Variable – something that is changed or can be manipulated by the scientist What is tested (the treatment) What is manipulated
10 3 Kinds of Variables Dependent Variable – something that might be affected or responds to by the change in the independent variable What is observed What is measured The data collected during the investigation (the result of the treatment)
11 For Example:
12 Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle.
13 Identify the variables in this investigation.
14 What was the independent variable? Ages of the students Different ages were tested by the scientist
15 What was the dependent variable? The time it takes to put the puzzle together The time was observed and measured by the scientist
16 What was a controlled variable? Same puzzle All of the participants were tested with the same puzzle. It would not have been a fair test if some had an easy 30 piece puzzle and some had a harder 500 piece puzzle.
17 Another example:
18 An investigation was done with an electromagnetic system made from a battery and wire wrapped around a nail. Different sizes of nails were used. The number of paper clips the electromagnet could pick up was measured.
19 What are the variables in this investigation?
20 Independent variable: Sizes of nails These were changed by the scientist
21 Dependent variable: Number of paper clips picked up The number of paper clips observed and counted (measured)
22 Controlled variables: Battery, wire, type of nail None of these items were changed
23 One more:
24 The higher the temperature of water, the faster an egg will boil and cook.
25 Independent variable – temperature of water Dependent variable – time to cook an egg Controlled variable – type of egg
26 Last one:
27 The temperature of water was measured at different depths of a pond.
28 Independent variable – depth of the water Dependent variable – temperature Controlled variable – thermometer
29 Designing Investigations
30 The greater the amount of soap in a soap and water mixture, the bigger a soap bubble can be blown. Design an investigation to test this hypothesis. Identify the variables What exactly will be changed? How will it be changed? What exactly will be measured? How will it be measured?
31 The farther a ball drops, the higher it will bounce. Design an investigation to test this hypothesis. Identify the variables What exactly will be changed? How will it be changed? What exactly will be measured? How will it be measured?
32 4. Collecting Data Data is data, it isn't right or wrong - presented in tables, charts, notes or diagrams. Two Types Quantitative Qualitative
33 Quantitative Data quantity - measured in numbers Qualitative Data quality - measured in words (descriptions) Types of Data
34 5. Analyzing Data Make interpretations of data by graphing data, correlating data with facts, using mathematical analysis etc.
35 6. Conclusions Report data - put your numbers into words. Answer: What was found out and how do you know it to be true? How did it relate to your hypothesis? Did it support or fail to support?
36 Analyze process and repeat All valid data is reproducible
37 Communication Share the results of their studies with other scientists Publish findings in journals or at scientific meetings Sharing of information is essential to scientific process Subject to examination and verification by other scientists Allows scientists to build on the work of others
38 Forming a Theory A theory may be formed after many related hypotheses have been tested and supported with experimental evidence A broad and comprehensive statement of what is thought to be true Supported by considerable evidence Ties together related hypotheses
39 Theory Explanation supported by a large amount of evidence obtained from many different investigations over a long period of time. Common Misconception: Theory defined as a guess is not the scientific definition. Example: Theory of Evolution
40 Law “Proven” theory - a theory explains a law Examples: Law of Gravity, Law of Conservation of Energy, Law of Conservation of Matter
41 Measurements We will be using SI (International System of Measurement ) units or metric system when possible --- get use to it --- the WHOLE world uses it except us (USA) Examples: length in meters, volume in liters, temperature in Celsius, mass in grams and time in seconds.
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