During a well-child visit, the nurse is assessing a 4-year-old child to evaluate developmental milestones specific to the preschool age group (3-6 years). The nurse notes that the child demonstrates imaginative play, has a vocabulary of 1,500 words, and articulates sentences comprising five to six words. Which of the following developmental tasks is most appropriate for this child's age according to the developmental milestones for preschoolers?