# Scientific Method Observations, Inferences, and Controlled Experiments.

Post on 28-Dec-2015

213 views

Category:

## Documents

Embed Size (px)

TRANSCRIPT

• Scientific MethodObservations, Inferences, and Controlled Experiments

• Scientific method.A systematic method of solving problems

All scientific knowledge is based on accurate observations of the natural world.

• Step 1 - ObservationsObservation - what is sensed or measured.An Observation is an act of carefully watching something and collecting facts. - Good scientific observations should be: Accurate Quantify or measure whenever possibleDetailed and Complete Consider all parts of the observation Repeatable All observers see the same thing or each time the event is observed the description is the same

• There are two types of observations: a) Qualitative ObservationsAn observation that describes the physical characteristics or qualities of something. (Ex. The water is hot; The M&M is small; The egg smells bad; The leaf is orange, etc) b) Quantitative ObservationsAn observation that is based upon numerical information or a measurement of some type. (Ex. The water is 45C; The M&M is 1.7 cm in length; The car is traveling at 65 Km/hr)

• Good scientific observations are used in order to make predictions, or inferences, about the natural world. They also allow us to formulate a Hypothesis

• Step 2 Form a HypothesisA possible answer to our question.

Or a possible explanation about an observation.

A Hypothesis should be supported by our observations and logical given our background knowledge.

• Step 3 - ExperimentsSet of controlled experiments designed to test a hypothesis.leads to new observations,If experiments do not prove our hypothesisDo more experiments, orFormulate a new hypothesis and start over!

• Controlled Experiments An experiment is basically a comparison of two situations.

One of the situations is left constant, while one factor of the other situation is changed in order to test the affect of that specific change.

Control a set of conditions used for comparison purposes; can either be original conditions, real-life conditions, or specific conditions set by the experimenter

• There are three types of factors that may affect an experiment. These factors are called variables.

1. The factor that is purposely changed by the experimenter is called the independent variable (also called the manipulated variable).2. The factor that changes in response to the independent variable is called the dependent variable (or the responding variable). 3. The rest of the factors that the scientists keep the same in the experiment are called the controlled variables.

• It is important to test the affect of changing only one variable in order to get accurate results.

**If only one variable is changed and all the other factors are kept the same then we say that it is a controlled experiment.

***Uncontrolled conditions can lead to inaccurate results!!!!

• Step 4 Conclusion or Theory

Sometimes the process just ends with a conclusion.Examples the substance is baking soda, or the substance is cocaine.

Or a Theory is formulated, A theory is a broad, general explanation that is developed for why things behave the way they do.Sometimes a model is developed.Like the model of the atom.

• Theory vs. Law

Theory an explanation that has been supported by many experiments.Theories are always subject to new discoveries and are modified to include new data.Example The dinosaurs became extinct after a large asteroid hit earth and blocked out all the light.

The true test of a theory is if it can predict new behaviors.If the prediction is wrong, the theory must be changed.

• Scientific Law

Scientific Law Describes a relationship in nature that is supported by many experiments and for which no exception has been found. It is always true.Laws are summaries of observations and are often a mathematical relationship.Examples - A gas will expand when heated. Mass and Energy will be conserved.

• ObservationsMore Observations

**