Twenty-three parent/child dyads (16 normally developing and 7 developmentally delayed preschoolers) were observed in a study to describe the verbal-logical behaviors and content expressed while they were engaged in teaching/learning interactions, and to determine if the structure of the activity, the sex and/or the developmental status of the children, or the sex/role of the parents influenced those behaviors. Dyads engaged in a semi-structured free play activity followed by a structural block sorting task. An observation system was used which permitted coding of verbal behaviors in terms of linguistic forms, communicative functions, and content references. Results of analyses of variance revealed that the activity factor had the greatest impact on the expressed behavior. The activity influenced both parent behavior (including frequencies of initiating, asking questions, and giving orders) and child behavior (such as soliciting, requesting or providing substantive information, and cooperating). The only behaviors differentiating groups of parents and their children were their verbalizing and references to spatial relationships and classification. The activity also exerted the most influence on sequences of behaviors. Few parent sex/role differences were observed. (CL)