6 weeks old: Child does not follow moving people with gaze and does not smile when spoken to

3 months old: Child does not raise head and chest off floor when lying on stomach.  Child can not grasp objects

6 months old: Child can not roll from stomach to back.  Child can not move objects from hand to hand.

9 months old: Child is unable to sit without support. Child is not crawling.

12 months old: Child is not saying at least one word. Child does not imitate people.

18 months old: Child is not walking independently. Child is unable to point to named pictures. Child is unable to drink from a cup.

2 years old: Child is not speaking two-word sentences. Child does not ask for food or water. Child can not climb on and off furniture.

3 years old: Child can not stand momentarily on one foot. Child does not use multiword sentences, or asks frequent questions

4 years old: Child can not walk up and down stairs. Child can not his/hers full name