Scientific Inquiry and The Scientific Method

Ask a Question or Recognize a Problem Identify the problem you are trying to solve or the question you are trying to answer Example – you wonder if your dog will grow to the size of Clifford the Big Red Dog if you feed him Protein supplements That is a question that needs to be answered

Good Observations are… Make Observations Statements of FACT Non-judgmental –No opinion involved They offer no conclusions or answers Good Observations are… Accurate Detailed As brief as possible! For example – “When the chemicals mixed, the solution turned blue and a sour odor was detected.”

Create a Hypothesis A hypothesis is an educated guess based on observations. The hypothesis must be TESTABLE or it isn’t useful It is specific to one situation and is in the form of an “if – then” statement It is created BEFORE any testing can take place

Hypotheses It clearly states one problem and the believed answer to that problem. For example – “If hydrochloric acid mixes with sodium, then hydrogen gas will be given off.” A hypothesis often sounds like a statement of fact, but it has yet to be tested.

Experimentation Once a scientist makes a hypothesis, it is tested using an experiment. The experiment will either nullify (prove wrong) or verify the hypothesis.

Experimentation Controlled Experiments Must Have Control group The control is used as a comparison – it shows beginning conditions – nothing is changed Experimental group This group has one (and only one) factor that changes (or varies) – this allows you to determine exactly what happened

Experimentation Controlled Experiments Must Have In any experiment there is a dependent variable and an independent variable The independent variable causes changes to the dependent variable For example: (observation) - as temperature decreases, trees’ leaves begin to change color (Hypothesis) – If the temperature drops (independent) then the leaves’ color changes (dependent)

Experimentation Controlled Experiments Must Have Constants – everything kept the same between the two groups except for the one variable being tested Without constants, you can’t tell if the independent variable caused the change or if something else did

Data Analysis Data collection and analysis are NOT the same thing Data collection – take various measurements using tools or instruments Data analysis - changing the form or modeling the data to draw conclusions Examples Calculating accuracy or precision Creating and interpreting graphs Calculating averages (mean, mode, median)

Conclusions Once you have collected and analyzed your data, you must draw a conclusion. Your conclusion answers whether you not your hypothesis was correct Your conclusion includes data that clearly supports or denies your hypothesis

Conclusions If a hypothesis is rejected (nullified); then it can either be revised for additional testing or it can be tossed aside and forgotten. If a hypothesis is verified, then it is tested over again and is subject to scientific scrutiny before it is accepted.

The steps do NOT have to go in order

Verified Hypotheses All verified hypotheses are subject to intense review by other scientists. many rejected by the scientific community for reasons (not limited to): poor experimental design, faulty logic, or imprecise conclusions. If a hypothesis passes this detailed review period, then it can be added as a principle or “law ”.

Principles or Laws Scientific “laws” refer to specific ideas that have not been contradicted by testing Ex: The Universal Law of Gravitation

Theories Theories link many scientific principles or laws together They explain a wide variety of phenomena observed in the natural world. They are NOT guesses!! For example – plate tectonics explains why fossils of the same species are found on opposite sides of the ocean AND why earthquakes occur in certain zones. While theories are always subject to revision, they are firmly accepted by the scientific community October 14, 2019

Summary Observations are facts without judgments. Inferences are based on observations. Hypotheses are educated guesses based on inferences. Experiments test hypotheses. Conclusions state whether or not hypothesis is verified or nullified Principles (“laws”) are based on accepted hypotheses. Theories are the combination of well-tested hypotheses and principles that explain many aspects of the natural world.

Summary (continued) Independent Variable (IV) – the variable that the scientist controls during the experiment Dependant Variable (DV) – the variable that changes due to the scientist manipulating the independent variable Experimental Group – The group that is being tested (or manipulated) Control Group – The group that remains unchanged so it can be used for comparison October 14, 2019