| Term | Definition |
| illusion | This decieves a person into believing something that is not true |
| measurement | comparison of an unknown quantity toa known, standard quantity |
| calibration | the marks on a measuring instrument, such as those showing mm and cm on a ruler |
| mistake | a ''goof'' that results in incorrect data |
| systematic error | error that causes all data values to vary from accepted values in the same way can be corrected with math |
| random error | error that results in data values that are too large or too small, cannot be corrected with math |
| classification | example: chemists group compounds by the type of chemical bonds |
| pattern | a trend in data that allows a prediction to be made |
| error | variations that occur even when a scientific procedure is followed properly |