preschool 3 year old milestones to 5 appsessment 3 3 developmental social development in 3 5 year olds important milestones your baby by child development at 3 4 years pediatric developmental milestones child development milestones for 3 child development at 3 4 years important milestones your baby by early childhood development chart 3rd important milestones your baby by child s development 3 to 5 years child development at 3 4 years child development at 3 4 years child development at 3 4 years important milestones your baby by