Five Things We’ve Learned About How Babies Develop

One · Together

Early skills develop together.

When your baby lifts their head, they can see more of the world and find new ways to respond to you. It’s one example of how movement, learning, communication, and relationships connect.

PhysicalLifts their head

…and that one skill opens new possibilities:

↓

Cognitive

Sees more of the room

Language

Can turn toward your voice

Social-emotional

Has more face-to-face moments with you

Early on, the four areas grow closely together.

As children get older, each area begins to follow its own path, while still influencing the others.

The connection between the four areas falls by almost half during the first year, then remains more stable through the ages shown · Kinedu record, 2020–2023 · children observed at consecutive ages between 2 and 35 months · technical name: within-child coupling

Two · In order

Skills build on earlier skills.

Babbling helps lay the groundwork for words. Pulling up to stand helps prepare the way for independent steps. These sequences help us understand what a child may be working toward.

Lifts their head≈ 3 mo

↓

Sits≈ 7 mo

↓

Stands≈ 12 mo

↓

Walks≈ 13 mo

Expected age: when three in four children have the skill · The order is typical, the timing varies · Kinedu record

From babbling to first words.

As children develop early speech, the assessment shifts its focus from babbling to words.

Average share of “yes” answers across the milestones in each skill group, by age · Kinedu record, 2020–2023 · shaded band ±1 SD

From first steps to more confident movement.

This skill group includes several milestones, from taking first steps to more advanced movement.

Average share of “yes” answers across the milestones in this skill group, by age · Kinedu record, 2020–2023

Three · Wide

Children reach milestones across a wide range of ages.

For some skills, children reach them within a few months of one another. For others, the range spans well over a year, and it tends to widen as children grow.

Learning to walk8–13 mo · 5 months wide

Dressing and feeding themselves17–39 mo · 22 months wide

02142 months

Each bar spans the ages at which 25% and 75% of children in the Kinedu record were reported with the milestones in that skill group.

An expected age is a reference point, not a deadline.

Four · Windows

A learning window isn’t a countdown.

The chart shows when reports of these skills become more common in our data. These age ranges describe a pattern, not a deadline for an individual child.

Exploring objects1–5 mo

First steps8–13 mo

First words14–25 mo

01326

Five · Unpredictable

Your child’s pace can change.

What your child is doing today doesn’t tell us how quickly the next skill will come. Where they are today and their pace of development are different things.

The chart below looks at a different question: how much an earlier assessment tells us about a child’s skill level later on.

An assessment is a snapshot, not a prediction.

Each assessment captures a moment in your child’s development. Checking in again helps you see what has changed.

In this analysis, current skill level explained about 1.5% of the variation in subsequent developmental pace.

Five things we’ve learned about how babies develop.

Five patterns that help explain development.