What is an Hypothesis?

HYPOTHESIS Sometimes scientists use a HYPOTHESIS to help guide an experimental investigation.

HYPOTHESIS A hypothesis is a special kind of PREDICTION. It is an educated statement about the relationship between the independent and dependent variable.

HYPOTHESIS A hypothesis is testable; an experimental investigation can be done based on the hypothesis.

How to write a HYPOTHESIS One way to write a hypothesis is to use an “If…, Then….” statement. An If, Then statement shows cause and effect.

How to write a HYPOTHESIS In other words, what effect does the independent variable have on the dependent variable? Or what does the independent variable cause the dependent variable to do?

How to write a HYPOTHESIS IF the independent variable changes, THEN the dependent variable will change. Of course, in a real hypothesis, you will state the actual variables and describe the type of changes you expect.

EXAMPLE If I eat too much chocolate (independent variable), then my face will break out in pimples (dependent variable.)

EXAMPLE If the plant receives fertilizer,(fertilizer is independent variable) than the plant that receives fertilizer will grow larger than the plant that does not receive fertilizer (plant is the dependent variable.)

VARIABLES Independent variable (Manipulated) What I change.

VARIABLES Dependent Variable (Responding) What I observe.

VARIABLES Controlled Variables What I keep the same.

QUESTION? Does a fertilizer make a plant grow bigger?

INDEPENDENT The amount of fertilizer in grams. Does a fertilizer make a plant grow bigger?

DEPENDENT The growth of the plant measured by its height. Does a fertilizer make a plant grow bigger?

CONTROLL Same size pot for the plants. Same type of plant. Same amount of soil and light exposure. Same amount of water.

HYPOTHESIS If the plant receives fertilizer,than the plant that receives fertilizer will grow larger than the plant that does not receive fertilizer.

Scientific Theory Some scientific theories include the theory of evolution, the theory of relativity, the atomic theory, and the quantum theory. All of these theories are well documented and proved beyond reasonable doubt.

Scientific Law Scientific laws must be simple, true, universal, and absolute. Some scientific laws, or laws of nature, include the law of gravity, Newton's laws of motion, Boyle's law of gases, and the law of conservation of mass and energy.

Theories and Laws In general, both a scientific theory and a scientific law are accepted to be true by the scientific community as a whole. Both are used to make predictions of events. Both are used to advance technology.

Scientific Models Scientific models help make sense of the world scientists create models. These models are powerful tools to help scientists predict the results of experiments.

3 Types of Scientific Models Physical

3 Types of Scientific Models Computer

3 Types of Scientific Models Idea

Benefits of Scientific Models Help communicate ideas Test predictions Save time, money, and lives.