The distinctive properties of stimuli, such as size, shape, position, and color, that enable one stimulus class to be discriminated from another. Stimuli that share a number of critical features often can be grouped to characterise a particular concept. For example, stimuli sharing the features of being alive-having fur, a backbone, and a spinal chord; or suckling young-characterize the concept "mammal." Yet other critical features shared only among subsets of the stimuli, such as particular shapes, habits, genetic qualities, and so on, distinguish one subclass of stimuli from another, as with different species of mammals. Daily report card. A contingency arrangement among the educational personnel, students, and their families, and designed to coordinate the contingencies across settings. In one setting (usually the school), the teacher marks a card contingent on the presence or absence of the target behaviour and sends it each day to the other setting (usually the home), where a delayed consequence is presented.