Infants typically start to roll over from tummy to back and back to tummy between 4 and 6 months of age.

Babies typically start to sit up without support between 6 and 8 months of age.

Infants typically start to crawl between 8 and 10 months of age.

Toddlers typically start to walk between 12 and 15 months of age.

Children typically start to speak their first words between 12 and 15 months of age.

Children typically start to put two words together to form simple sentences between 18 and 24 months of age.

Developmental coordination disorder is a significant delay in the development of motor skills, such as walking or talking.

Specific language impairment is a condition in which a child has difficulty understanding or using language.

Attention deficit hyperactivity disorder is a condition in which a child has difficulty paying attention, controlling impulsive behavior, or managing emotions.

Specific learning disability is a condition in which a child has difficulty learning and using academic skills, such as reading, writing, or math.

Autism spectrum disorder is a condition in which a child has difficulty with social interactions and communication.

Oppositional defiant disorder is a condition in which a child has difficulty controlling their emotions and behavior.

Conduct disorder is a condition in which a child has difficulty following rules and authority figures.

Intermittent explosive disorder is a condition in which a child has sudden, uncontrollable outbursts of anger and aggression.

Dyslexia is a condition in which a child has difficulty with reading, writing, or math, but has average or above average intelligence.