Final answer:
A small group is defined as a group where all members know each other and engage in simultaneous interaction. Examples of small groups include a nuclear family, dyads, and triads.
Step-by-step explanation:
A small group, as defined by the textbook, is a group where the collection of people is small enough that all members know each other and engage in simultaneous interaction. Examples of small groups include a nuclear family, a dyad (a two-member group), and a triad (a three-member group). In a dyad, if one person withdraws, the group can no longer exist, whereas in a triad, the group can continue even if one person withdraws.