Steps of a Scientific Investigation

We all observe the natural world and ask questions about these observations. A scientific investigation is a way of answering these questions.

Science is a human activity that attempts to explain and accurately describe nature by raising and answering descriptive and causal questions.

Descriptive question A question inquiring into the who, what, when, where - but not why - of some observed object, event, or situation. For example What types of vegetation changes occur as one travels from the bottom of a mountain to the top? Where is Mount Si? What is the temperature at the summit of Mount Si? When were mountain goats last seen on Mount Si?

Causal question A question inquiring into the cause or causes of some phenomenon. For example: What causes the vegetation change as you hike from the base to the summit of Mount Si? Why is it cooler at the top of Mount Si than at the bottom? Causal questions seek causes – explanations - for puzzling observations.

When doing science the investigator assumes that the natural world is understandable and can be explained by fundamental rules or laws.

The following guideline can be used to find plausible answers to these questions.

What is the name of the process used to answer these questions scientifically? The scientific method.

When posed with a particular problem or in an attempt to answer a puzzling observation, an individual pursuing an answer through scientific inquiry develops (or uses one already developed) a well-crafted question and transforms it into a _________________?

By the way, what is a hypothesis By the way, what is a hypothesis? (and it’s more than an educated guess ) A hypothesis is a tentative explanation that can be tested. The scientific method is limited to only those explanations that are testable.

A scientific investigation uses deductive reasoning Deductive reasoning is an if/and/then pattern of reasoning in which a statement and an imagined test condition together allow the derivation of an expected consequence.

Steps of a scientific investigation A puzzling observation is made that raises 2) a causal question. 3. One or more tentative explanations (hypotheses) are generated. 4. A test (experiment) is planned that allows the generation of a prediction. 5. The planned test is conducted and its result is observed. 6. The observed result is then compared with the predicted result. (analysis) 7. A conclusion is drawn about the status of the tested explanation based on the match or mismatch of prediction and results. (support/not support of hypothesis and why?)

How would you define an experiment? It is a test of a hypothesis. Design an experiment. How would you define an experiment? It is a test of a hypothesis.

Pre-Lab Flow Chart Pre-lab flowchart elements If…… and… then.. Therefo Purpose or Question Controlled Variable(s) (constant across treatments) (identify at least 3) Hypothesis “proposed explanation” Responding Variable (Y axis) (dependent) (what you are measuring?) Manipulated Variable (X axis)(changed/independent) Procedure “methods” Treatments levels? control? Experimental design (between dashed lines) Predicted Result of Experiment If…… Observed Result of Experiment Conclusion then.. And/But… Therefo and… Pre-lab flowchart elements Therefore…..

Responding Variable: The variable that you are measuring.(it is what you count or record in your data table). Examples?

Manipulated Variable The variable that you vary (manipulate) during the experiment. It is the variable that you think will affect the responding variable.

Treatments Appropriate levels (values) that you assign to the manipulated variable. Examples?

Controlled Variable(s) All manipulated variables other than the one being studied that are to be held constant.

Do we run the experiment now?

A prediction needs to be made before you run the experiment. What is a prediction? A prediction is the expected result of an experiment (your “educated guess”). Usually it takes the form of an “if  then” statement. Your prediction has to be based on your hypothesis.

Collect data. What is data? It is the actual results of your experiment. (not the character on Star Trek)

Analysis (Discussion of Results) Using the data you collected directly from the experiment, make meaning of the data to determine a relationship between the variables of the experiment. Communicate your understanding of this relationship from what the data evidence has displayed for you from your results.

Form a conclusion. What is a conclusion? A conclusion is a statement on whether your hypothesis is supported or not. If your data = your prediction, then your hypothesis is supported. If your data = your prediction, then your hypothesis is not supported.