Physical Development and Milestones

An order, not a timetable

Physical development is usually met as a list of things babies do and the ages they do them at, which is the least useful version of it and the one that worries people. Milestones are an ORDER, not a timetable. The sequence is highly reliable, and the reason is physical: each stage is built on the one before it. A baby cannot sit until the neck and trunk can hold the body upright. They cannot walk until balance and leg strength have been built by sitting, pulling up on furniture and moving around while holding on. You cannot skip a step because the next one needs what the last one built. The ages are averages, and the normal range around them is wide. Two children who reach the same stage months apart are both developing normally, and that is ordinary rather than remarkable. So this module gives almost no ages at all, on purpose. The question to carry through it is the one that actually explains the sequence: what does this stage make possible next? The other strands of development, and play, are the other modules on this part of the course.

Five words used precisely

The first two are the pair everything else sorts into, and the last one is the one most often misread.

Two that use the small muscles

Five things a young child might be doing. Tap the TWO that are fine motor skills.

• Climbing onto a low step and back down again
• Threading large beads onto a string
• Running across a room without falling over
• Holding a spoon and getting most of the food into their mouth
• Throwing a soft ball with both hands

Two children, months apart

Two children in the same family group both start walking, but one of them reaches it several months later than the other. Both had good head control and sat steadily before they walked. What does this tell you?

• That both followed the usual sequence, and that the gap between them is ordinary, because the normal range for reaching a stage is wide
• That the later child is behind and needs help to catch up
• That the earlier child is more physically able and will stay ahead
• That the later child must have skipped a stage

Big muscles first, and from the middle out

One pattern explains both lists, so neither has to be memorised: control arrives at the head before the trunk and the trunk before the legs, and at the shoulder before the elbow, the elbow before the wrist and the wrist before the fingers.

Five stages, five different things they unlock

Put the sequence in order

Six stages of large-muscle development. Put them in the order they are usually reached. No ages are given, because the order is the reliable part.

• Holding the head steady when held upright
• Rolling over from front to back
• Sitting without support
• Moving about the floor, by crawling, shuffling or another method
• Pulling up to stand against furniture and moving along it
• Walking unaided

What a strong answer does here

Three habits, and the first one is worth more than any list of ages. Explain the order by what it builds. Saying a baby sits before it walks is a fact anybody has. Saying that sitting develops the trunk strength that standing and balance need is an explanation, and explanations are what the longer questions are asking for. Say that the range is wide, and mean it. An answer that treats an age as a deadline gets the subject wrong. Variation between children who are all developing normally is large, and saying so is not hedging: it is the correct description. ⭐ And read a centile chart as a line, not a dot. What is looked at is the pattern over time: a child tracking steadily along a lower centile is growing as expected. A single measurement on one day says very little on its own. Health professionals are the people who monitor this, and knowing what they are looking at is the part that belongs in an exam answer.

Which kind of skill

For each activity, decide which kind of movement it mainly needs. Three lives.

Two people learning to drive

Two adults start learning to drive in the same month. One passes after fifteen lessons and the other after forty. Nobody concludes anything much from that. People learn at different rates, they have different amounts of practice available, and one of them may simply have started more nervous. A year later, watching them both drive, you would not be able to tell which was which. But the ORDER is not negotiable for either of them. Neither can do a junction safely before they can steer smoothly, and neither can steer smoothly before they can control the car at low speed. An instructor who taught junctions first would not be moving faster; they would be wasting everybody time, because the later skill needs what the earlier one builds. ⭐ So the sequence tells you something real and the timing tells you very little. Anybody comparing the two learners by counting lessons is measuring the wrong thing.

What makes a strong explanation

A student writes that babies sit before they walk. Select every addition that would turn it into an explanation worth marks.

• Saying what sitting builds that walking needs
• Noting that the ages at which children do both vary widely
• Linking it to control developing from the head downwards
• Adding the average age for each of the two stages
• Listing several more stages in the same sequence

Finish the development sentences

Movements using the large muscles of the body, such as sitting, walking and climbing, are _____ motor skills. Movements using the small muscles of the hands and fingers, such as threading beads or using a spoon, are _____ motor skills. A stage most children pass through in a recognisable order is a _____, and it marks a point in a sequence rather than a deadline. The span of ages within which children typically reach one is the normal _____, and it is wide enough that two children months apart are both developing as expected. Control spreads from the head downwards and from the _____ of the body outwards, which is why steady shoulders come before steady fingers. A chart recording growth over time is a _____ chart, and it is read as a line rather than as a single point.

Build the explanation

A question asks why a baby sits before it walks. Assemble the answer that would earn most.

Four questions on one topic

A student is revising this topic and keeps running into the same kind of question. Each stage hands them a decision.

• They have made a revision card listing every milestone with an average age beside it, and cannot remember any of the ages. Decide what to do.
• A question asks them to explain why fine motor skills develop later than gross motor skills. Decide the strongest answer.
• A question shows a centile chart for a child whose measurements sit on a low centile but follow it steadily over two years. Decide what to say.
• A classmate says a child they know is walking later than a cousin did, and asks whether that means something is wrong. Decide what to say.

Explain the sequence

Explain why physical development happens in a reliable order, and why the ages attached to that order matter much less than the order itself.

• Explain the difference between gross and fine motor skills, with an example of each
• Give TWO stages in order and say what the first one builds that the second one needs
• Explain the direction control develops in, and what it accounts for
• Say what a normal range is, and why it matters that it is wide
• Explain how a centile chart should be read, and why a single measurement says little
• Finish by explaining why a list of average ages is the least useful way to learn this topic