Question

A 24-month-old boy is brought to the clinic for a routine well-child visit. His mother is concerned that his development is lagging behind his older sister's development at the same age. She notes that the patient walks up and down the stairs by placing both feet on each step before moving to the next. He enjoys kicking a ball but cannot yet pedal a tricycle. When playing with blocks, he successfully builds a tower of 6 cubes. His vocabulary consists of approximately 60 words, and he frequently uses 2-word phrases such as "want milk." His mother reports that strangers can understand about half of what he says. During a playdate, he plays next to other children but does not engage in cooperative play with them. He is not yet toilet trained. Physical examination is unremarkable. Which of the following is the most appropriate next step in management?