Infants typically start to roll over from belly to back and back to belly between 3 and 4 months of age.

Walking is typically a milestone achieved between 9 and 15 months, not between 6 and 9 months.

Infants typically start to recognize their own name between 9 and 10 months of age.

Object permanence is a cognitive milestone typically achieved during the sensorimotor stage, which lasts from birth to about 2 years of age.

Understanding simple commands is typically a milestone achieved between 18 and 24 months, not between 12 and 18 months.

Separation anxiety is a normal emotional response in infants and typically occurs between 8 and 18 months of age.

Understanding simple stories is typically a milestone achieved between 2 and 3 years of age, not between 18 and 24 months.

Active learning is a term used to describe the process by which infants learn about their environment through exploration and interaction.

Riding a tricycle is typically a milestone achieved between 3 and 4 years of age, not between 2 and 3 years.

The preoperational stage is the second stage of cognitive development according to Piaget's theory, and it lasts from about 2 to 7 years of age.

Understanding simple rules is typically a milestone achieved between 4 and 5 years of age, not between 3 and 4 years.

Stranger anxiety is a normal emotional response in infants and typically occurs between 6 and 9 months of age.

Understanding complex instructions is typically a milestone achieved between 4 and 5 years of age, not between 3 and 4 years.

Observational learning is a term used to describe the process by which infants learn about the world through imitation.

Riding a bike with training wheels is typically a milestone achieved between 5 and 6 years of age, not between 4 and 5 years.