We live in Colorado, USA. My son turned
Ask
We live in Colorado, USA.
My son turned 4 years old last month. At his preschool conference yesterday, the teacher noted that he cannot stand steadily on one foot for more than a second and cannot hop on one foot across the rug. She suggested we consider a motor delay evaluation.
We are worried and want to understand the objective developmental milestones.
1. Is standing on one foot or hopping on one foot an expected 4-year milestone, or is that later on the CDC developmental checklist?
2. What does the CDC 4-year gross motor milestone list actually include?
3. What is our concrete dated next step to discuss with our pediatrician at his upcoming well-child visit?
Answer
Short answer to your three questions: **neither** standing on one foot **nor** hopping on one foot is on the CDC 4-year checklist — both items are on the CDC 5-year page. So the teacher's two examples come from the year ahead, not the year your son just turned.
## What the CDC 4-year movement list actually says (75%+ by age 4)
- Catches a large ball most of the time
- Serves herself food or pours water, with adult supervision
- Unbuttons some buttons
- Holds crayon or pencil between fingers and thumb (not a fist)
Source: https://www.cdc.gov/act-early/milestones/4-years.html (accessed 2026-09-02)
The "75%+" means most children this age do these things — it is a population marker, not a pass/fail line for your son, and not a percentile you can plot at home.
**WHO windows:** the WHO motor-milestones table here only covers six gross-motor skills up to "walking alone" (8.2–17.6 months). One-foot standing and hopping are not on it, so I cannot quote a window for either of those.
## When the AAP/CDC framework says to screen
General developmental screening at 9, 18, and 30 months — **and also whenever concerned.** That last clause is what fits you: you don't have to wait for the next scheduled visit.
Source: https://www.cdc.gov/act-early/about/developmental-monitoring-and-screening.html (accessed 2026-09-02)
A visit already on the calendar is where this conversation happens, not a reason to push it to a later one.
## What to bring to the upcoming well-child visit
| Today (2026-09-17) | What it does |
| --- | --- |
| Write one dated line: "4 years old; preschool conference 2026-09-16; teacher noted cannot stand on one foot >1 sec, cannot hop one foot across the rug." | A specific dated observation is what a screening reads, not a general "seems behind" |
| Bring what he **does** do: runs, climbs, pedals a tricycle, stairs alternating feet, catches a ball | The picture of what's typical matters as much as what isn't |
| Add: "Has he lost any skill he used to have?" — answer No or describe | This is one of the four CDC share-with-doctor questions and is asked at every age |
At the visit, ask two specific things:
1. A **formal developmental screening** on top of the well-child check.
2. A referral to a developmental pediatrician or a physical therapist if the screen flags anything — and ask about the local early-childhood route (CDC points families there once a concern is on the table).
A4-year-old who is not yet standing or hopping on one foot is mostly at the front edge of the 5-year items — but "whenever concerned" still applies, and the screening is the way to tell which of those it is.
Does he run, climb, and pedal a tricycle? That would tell me whether what the teacher saw is one item or part of a larger picture.