For the first few years of life, humans are wonderfully comparable. By the time you have developed the capacity to read this blog, most of your physical development is probably complete. For some early stage of life, a complex organism is busy realizing its physical potential, and ramping up to a full realization of its capacity: for homo sapiens, this lasts years. There are many things at all ages that do not fit onto a linear model like this one, but early on, there are capacities every individual will develop, unless something goes wrong.
The Centers for Disease Control and Prevention (CDC) in the United States are recognized as an authority on categorizing human conditions with regard to disease. They have also published a list of human development milestones for parents to refer to when observing their children’s behavior. These milestones go up to age 5, at which point the child is an adult, and can start tracking the troubling development of their parents. The CDC sorts their developmental milestones into four categories: Social/Emotional, Language/Communication, Cognitive, and Physical Development.
Alternative sources give different presentations of these milestones, but all the sources I have encountered are organized by age of child primarily, and then each of those sections is sorted into domains/categories. I reversed the information hierarchy organizing these milestones: here, they’re presented by domain, with a common age of the child listed under that. I have some other ideas about what to do with these, but I am publishing them here in case anyone else is interested in this sort of presentation. I don’t think this is presented as well as it could be. I can imagine changing this in all sorts of ways, but I’m not going to do it immediately, so I figured I should publish this now. These milestones were originally presented by the CDC as a PDF: this format might be easier for you to manipulate. If you’d rather find something more computer-friendly, you might prefer to look at the source of this post.
Social/Emotional
2 Months
Begins to smile at people
Can briefly calm himself (may bring hands to mouth and suck on hand)
Tries to look at parent
4 Months
Smiles spontaneously, especially at people
Likes to play with people and might cry when playing stops
Copies some movements and facial expressions, like smiling or frowning
6 Months
Knows familiar faces and begins to know if someone is a stranger
Likes to play with others, especially parents
Responds to other people’s emotions and often seems happy
Likes to look at self in a mirror
9 Months
May be afraid of strangers
May be clingy with familiar adults
Has favorite toys
1 Year
Is shy or nervous with strangers
Cries when mom or dad leaves
Has favorite things and people
Shows fear in some situations
Hands you a book when he wants to hear a story
Repeats sounds or actions to get attention
Puts out arm or leg to help with dressing
Plays games such as “peek-a-boo” and “pat-a-cake”
18 Months
Likes to hand things to others as play
May have temper tantrums
May be afraid of strangers
Shows affection to familiar people
Plays simple pretend, such as feeding a doll
May cling to caregivers in new situations
Points to show others something interesting
Explores alone but with parent close by
2 Years
Copies others, especially adults and older children
Gets excited when with other children
Shows more and more independence
Shows defiant behavior (doing what he has been told not to)
Plays mainly beside other children, but is beginning to include other children, such as in chase games
3 Years
Copies adults and friends
Shows affection for friends without prompting
Takes turns in games
Shows concern for a crying friend
Understands the idea of “mine” and “his” or “hers”
Shows a wide range of emotions
Separates easily from mom and dad
May get upset with major changes in routine
Dresses and undresses self
4 Years
Enjoys doing new things
Plays “Mom” and “Dad”
Is more and more creative with make-believe play
Would rather play with other children than by himself
Cooperates with other children
Often can’t tell what’s real and what’s make-believe
Talks about what she likes and what she is interested in
5 Years
Wants to please friends
Wants to be like friends
More likely to agree with rules
Likes to sing, dance, and act
Is aware of gender
Can tell what’s real and what’s make-believe
Shows more independence (for example, may visit a next-door neighbor by himself [adult supervision is still needed])
Is sometimes demanding and sometimes very cooperative
Language/Communication
2 Months
Coos, makes gurgling sounds
Turns head toward sounds
4 Months
Begins to babble
Babbles with expression and copies sounds he hears
Cries in different ways to show hunger, pain, or being tired
6 Months
Responds to sounds by making sounds
Strings vowels together when babbling (“ah,” “eh,” “oh”) and likes taking turns with parent while making sounds
Responds to own name
Makes sounds to show joy and displeasure
Begins to say consonant sounds (jabbering with “m,” “b”)
9 Months
Understands “no”
Makes a lot of different sounds like “mamamama” and “bababababa”
Copies sounds and gestures of others
Uses fingers to point at things
1 Year
Responds to simple spoken requests
Uses simple gestures, like shaking head “no” or waving “bye-bye”
Makes sounds with changes in tone (sounds more like speech)
Says “mama” and “dada” and exclamations like “uh-oh!”
Tries to say words you say
18 Months
Says several single words
Says and shakes head “no”
Points to show someone what he wants
2 Years
Points to things or pictures when they are named
Knows names of familiar people and body parts
Says sentences with 2 to 4 words
Follows simple instructions
Repeats words overheard in conversation
Points to things in a book
3 Years
Follows instructions with 2 or 3 steps
Can name most familiar things
Understands words like “in,” “on,” and “under”
Says first name, age, and sex
Names a friend
Says words like “I,” “me,” “we,” and “you” and some plurals (cars, dogs, cats)
Talks well enough for strangers to understand most of the time
Carries on a conversation using 2 to 3 sentences
4 Years
Knows some basic rules of grammar, such as correctly using “he” and “she”
Sings a song or says a poem from memory such as the “Itsy Bitsy Spider” or the “Wheels on the Bus”
Tells stories
Can say first and last name
5 Years
Speaks very clearly
Tells a simple story using full sentences
Uses future tense; for example, “Grandma will be here.”
Says name and address
Cognitive
2 Months
Pays attention to faces
Begins to follow things with eyes and recognize people at a distance
Begins to act bored (cries, fussy) if activity doesn’t change
4 Months
Lets you know if she is happy or sad
Responds to affection
Reaches for toy with one hand
Uses hands and eyes together, such as seeing a toy and reaching for it
Follows moving things with eyes from side to side
Watches faces closely
Recognizes familiar people and things at a distance
6 Months
Looks around at things nearby
Brings things to mouth
Shows curiosity about things and tries to get things that are out of reach
Begins to pass things from one hand to the other
9 Months
Watches the path of something as it falls
Looks for things he sees you hide
Plays peek-a-boo
Puts things in her mouth
Moves things smoothly from one hand to the other
Picks up things like cereal o’s between thumb and index finger
1 Year
Explores things in different ways, like shaking, banging, throwing
Finds hidden things easily
Looks at the right picture or thing when it’s named
Copies gestures
Starts to use things correctly; for example, drinks from a cup, brushes hair
Bangs two things together
Puts things in a container, takes things out of a container
Lets things go without help
Pokes with index (pointer) finger
Follows simple directions like “pick up the toy”
18 Months
Cognitive (learning, thinking, problem-solving)
Knows what ordinary things are for; for example, telephone, brush, spoon
Points to get the attention of others
Shows interest in a doll or stuffed animal by pretending to feed
Points to one body part
Scribbles on his own
Can follow 1-step verbal commands without any gestures; for example, sits when you say “sit down”
2 Years
Finds things even when hidden under two or three covers
Begins to sort shapes and colors
Completes sentences and rhymes in familiar books
Plays simple make-believe games
Builds towers of 4 or more blocks
Might use one hand more than the other
Follows two-step instructions such as “Pick up your shoes and put them in the closet.”
Names items in a picture book such as a cat, bird, or dog
3 Years
Can work toys with buttons, levers, and moving parts
Plays make-believe with dolls, animals, and people
Does puzzles with 3 or 4 pieces
Understands what “two” means
Copies a circle with pencil or crayon
Turns book pages one at a time
Builds towers of more than 6 blocks
Screws and unscrews jar lids or turns door handle
4 Years
Names some colors and some numbers
Understands the idea of counting
Starts to understand time
Remembers parts of a story
Understands the idea of “same” and “different”
Draws a person with 2 to 4 body parts
Uses scissors
Starts to copy some capital letters
Plays board or card games
Tells you what he thinks is going to happen next in a book
5 Years
Counts 10 or more things
Can draw a person with at least 6 body parts
Can print some letters or numbers
Copies a triangle and other geometric shapes
Knows about things used every day, like money and food
Physical Development
2 Months
Can hold head up and begins to push up when lying on tummy
Makes smoother movements with arms and legs
4 Months
Holds head steady, unsupported
Pushes down on legs when feet are on a hard surface
May be able to roll over from tummy to back
Can hold a toy and shake it and swing at dangling toys
Brings hands to mouth
When lying on stomach, pushes up to elbows
6 Months
Rolls over in both directions (front to back, back to front)
Begins to sit without support
When standing, supports weight on legs and might bounce
Rocks back and forth, sometimes crawling backward before moving forward
9 Months
Stands, holding on
Can get into sitting position
Sits without support
Pulls to stand
Crawls
1 Year
Walks alone
May walk up steps and run
Pulls toys while walking
Can help undress herself
Drinks from a cup
Eats with a spoon
2 Years
Stands on tiptoe
Kicks a ball
Begins to run
Climbs onto and down from furniture without help
Walks up and down stairs holding on
3 Years
Climbs well
Runs easily
Pedals a tricycle (3-wheel bike)
Walks up and down stairs, one foot on each step
4 Years
Hops and stands on one foot up to 2 seconds
Catches a bounced ball most of the time
Pours, cuts with supervision, and mashes own food
5 Years
Stands on one foot for 10 seconds or longer
Hops; may be able to skip
Can do a somersault
Uses a fork and spoon and sometimes a table knife
Can use the toilet on her own
Swings and climbs