Designing an Experiment &The Characteristics of Scientific Knowledge

Bellringer  Chemists once believed that an atom was made of negative electrons dispersed inside a positive mass like raisins in pudding. An experiment with radiation and gold foil demonstrated that most of an atom was made of empty space. After this experiment, they adopted a new model of the atom that showed the electrons orbiting the nucleus of the atom from a distance. Which of the following statements about the new model is true?  The new model is perfect and will not change.  The new model is a wrong model and will not last.  The new model fits the data worse than the old model.  The new model fits the data better than the old model.

How do you conduct Scientific Inquiry?!?!  Scientific Inquiry is the process through which scientists ask and answer questions.  People conduct scientific inquiry by gathering evidence about the natural world and proposing explanations based on this evidence.  The first steps in the scientific inquiry process are posing questions, defining a problem and researching that problem. Next, develop a hypothesis, a possible answer to scientific question.

How do you test a Hypothesis?!?!?!  You test a hypothesis by designing an experiment that follows reliable scientific principles. A large part of designing an experiment is controlling variables.  The one factor that is purposely changed to test a hypothesis is the Independent Variable.  The factor that may change in response to the independent variable is the Dependent Variable.  A scientific experiment in which only one variable is tested at a time is called a control experiment.  If the variables are not controlled, it is impossible to tell which variable influenced the results. When designing experiments, scientists also have to be careful not to introduce bias, or an error in the design of the experiment. To eliminate bias, scientists use a good sample size and repeat experiments.

How do you test a Hypothesis?!?!?! Cont’d  After receiving the results from an experiment, scientists organize and interpret the data. Then they examine the data to draw a conclusion about whether the data supports the hypothesis. Before a hypothesis can be accepted as true, the experiment must be repeated many times with repeated trials.  Finally, scientists communicate their results. When communicating results, scientists include a description of the procedure so that other scientists can study it. A replication is an attempt by other scientists to conduct the same experiment.

What is a Scientific Explanation?  In some branches of Science it is difficult to perform controlled experiments. Scientists in these fields must develop a scientific explanation. A scientific explanation is a generalization that makes sense of observations by using logical reasoning.

What Activities Do Scientific Investigations involve?  Scientific Investigations involve observing, collecting empirical evidence, using logical reasoning, inferring, and applying imagination.  Observing means using one or more of your senses to gather information. Observing is the process of gathering information from which scientific conclusions are drawn.  Data are facts, figures and other evidence collected during a scientific investigation.  Empirical evidence is data and observations that have been collected through scientific processes and that also explain a particular observation. All scientific investigations involve the collection of relevant empirical evidence to support researchers’ conclusions.

What Characterizes Science and its Methods?!?!?!?!  Science and its methods are characterized by an ordered approach to learning about the world. This approach relies on objective analysis of data obtained through careful investigation. Because scientific investigations are well- reasoned, they can be repeated by other scientists to confirm results.  Although science is based on empirical evidence and objective reasoning, it results are open to new discoveries and change. Sometimes new data may be so unexpected that scientist rethink earlier hypotheses entirely.