Final answer:
A nurse would likely see 4-year-old children in the hospital playroom playing cooperatively with other preschoolers as part of their cognitive and social development.
Step-by-step explanation:
When observing 4-year-old children playing in the hospital playroom, the nurse would most likely expect to see the children participating in playing cooperatively with other preschoolers. At this age, children are developing socially and cognitively, engaging in pretend play, and learning to cooperate with peers. They may play side by side, but typically by 4 years old, children have begun to develop the skills needed to play together and cooperate on shared activities such as building with blocks, drawing, or making up games. This cooperation is part of their social and emotional development, contributing to a positive sense of self and understanding of social norms.