Physical and motor-skill markers:

• Should have doubled birth weight (birth weight often doubles by 4 months, and it would be concerning if it hasn't happened by 6 months)
• Able to lift chest and head while on stomach, bearing the weight on hands (often occurs by 4 months)
• Able to sit in a high chair with a straight back
• Beginning of teething
• Increased drooling
• Able to bear almost all weight when supported in a standing position
• Able to roll from back onto abdomen
• Able to hold own bottle (but many babies won't do it or only for short periods)
• Able to pick up a dropped object

Sensory and cognitive markers:

• Vision is between 20/60 and 20/40
• Can locate sounds not made directly at the ear
• Prefers more complex sound stimulation
• Starts to imitate sounds
• Sounds resemble one-syllable words
• Enjoys hearing own voice
• Makes sounds to mirror and toys
• Begins to fear strangers
• Recognizes parents
• Begins to imitate actions
• Begins to realize that if an object is dropped, it is still there and just needs to be picked up

Play recommendations:

• Provide a mirror that is unbreakable
• Provide large, bright colored toys that make noise or have moving parts
• Play peek-a-boo
• Provide paper to tear
• Speak clearly
• Imitate words such as "mama" to facilitate learning of language
• Start naming parts of the body and the environment
• Use the word "no" INFREQUENTLY
• Use body movements and actions to teach language