Between ages 3 and 4, children make significant developmental leaps. They master gross motor skills like running, jumping, and riding a tricycle, and refine fine motor skills by drawing circles and squares, using safety scissors, and dressing themselves with minimal help. Language skills expand rapidly; they use sentences of four or more words, ask "why" questions, and understand prepositions and basic opposites. In cognitive development, they can sort by shape and color, understand the concept of counting, and engage in imaginative play. Socially and emotionally, they're learning to share, take turns, express a wider range of emotions, and are more cooperative with others.