Office of Science PreK-12

brainstorming	experiment	procedure	trial
conclusion	hypothesis	question	variable
control variables	independent variable	qualitative data
data	material	quantitative data	Other:
dependent variable	observation	results	Word Central

brainstorming

Brainstorming is a technique for coming up with ideas.

conclusion

A conclusion is a summary of the results of an investigation (experiment) and whether the hypothesis was verified.

control variables

The control variables are the factors in the investigation (experiment) that must be kept exactly the same to make sure that they are not having any effect on the dependent variable. In other words, the control variables are the factors that you make identical for each trial of your investigation, so that only the independent variable changes. For example, if you are testing how the length of a string affects a pendulum, your control variables would include the type of string used, how the string is attached, etc.
Tip: You will probably have more than one control variable.

data

Data are pieces of information; facts.

dependent variable

The dependent variable is the factor that is observed and measured to see if it is affected by the change made in the independent variable. In other words, the dependent variable is the variable that responds to your investigation (experiment). An example of a dependent variable is the number of swings the pendulum makes when the length of string is changed.

Tip: You should have only one dependent variable.

experiment

An experiment is a series of actions and observations of the consequences to tell if a hypothesis is verified or not.

hypothesis

A hypothesis attempts to predict the outcome of the investigation (experiment) and suggests a possible reason for this outcome. The hypothesis should be based on research and/or prior knowledge / observations. The hypothesis is proven true or untrue by the investigation.

independent variable

The independent variable is the factor that the researcher intentionally changes during the experimental procedure in order to find out what effect it has on something else. In other words, the independent variable is the variable that is manipulated (changed) on purpose. An example of an independent variable is using different lengths of string to construct a pendulum in order to observe the effect the length of the string has on the swing of the pendulum.

Tip: You should have only one independent variable.

materials

Materials are the things you use in an investigation (experiment). Materials used in the investigation need to be listed in specific amounts and sizes (example – three five gram weights).

observation

An observation is watching something and recording what happens (example - the water is cloudy).

procedure

Procedures are the steps of the investigation (in other words the directions). The procedure used in an investigation (experiment) must be written in a clear, sequential manner in order to allow someone else to follow the same steps to duplicate the investigation.
Tip: Numbering the steps followed in the procedure is helpful to someone who is reading the procedure.

question

Good science investigations begin with a question. This question often asks “what if,” “how,” or “what effect something will have.” The question should be one that can lead to an investigation (experiment) which will yield data.

qualitative data

Qualitative data are variables that can be represented by an attribute or classification (example - the grass is green).

quantitative data

Quantitative data are variables that can be represented by measurements with numbers (example - the boy is 45 inches tall)

results

The results of the investigation (experiment) include the measurements taken and observations made as well as a written explanation of the outcome (what happened).

trial

A trial is a single repetition of an investigation (experiment). For an investigation to be reliable, you need to do more than one trial. You should do 3 trials (for example, bounce each ball 3 times in order to calculate a mean (average) bounce height).

variable

Variables are the factors that will affect the outcome of the investigation (experiment). For example, a pendulum swinging on a string is affected by the length of the string, the weight of the pendulum, etc.

For definitions of other terms, visit Word Central.

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