2. Classification Process of grouping Binary classification: Sorting objects into 2 groups based on a particular property Multistage classification Serial classification: sorting objects in a logical order on the basis of the extent or degree to which they demonstrate a common attribute Dichotomous key: a tool that scientists can use to help identify a particular specimen
5. Measurement Quantify variables using a variety of instruments and nonstandard/standard units Nonstandard units: it is difficult to consistently compare objects that cannot be held side by side Standard units: enable consistent descriptions and comparisons of measured objects that are not side by side and cannot be directly compared