Most Likely Age: 48 Months
Based on the described motor skills—particularly the ability to hop on one foot multiple times without losing balance—this child is most likely 48 months (4 years) old.
Developmental Analysis
Key Discriminating Skill: Hopping on One Foot
The ability to hop on one foot multiple times without losing balance is the critical milestone that determines this child's age 1. This skill typically emerges around 48 months and represents advanced motor planning and balance capabilities that distinguish 4-year-olds from younger children 1.
Supporting Motor Skills by Age
Skills consistent with 30 months:
- Running and jumping off ground with both feet are typically achieved by 24-30 months 2, 3
- Kicking a large ball emerges around 24-30 months 1
Skills consistent with 36 months:
- Alternating feet going up and down stairs typically develops around 36 months 1
- Catching a ball with both hands consistently becomes more reliable around 36 months 1
Skills requiring 48 months:
- Hopping on one foot multiple times without losing balance is a complex motor task requiring sequential motor planning (praxis), balance, and coordination that typically emerges at 48 months 1
- This skill represents the integration of strength, coordination, and motor planning that characterizes the 4-year-old developmental stage 1
Walking History Context
The child's independent walking at 13 months falls within normal developmental parameters, as 75% of children walk independently by 14 months and the American Academy of Pediatrics identifies 18 months as the upper limit of normal 2. This normal walking onset supports typical overall motor development trajectory 2.
Clinical Reasoning
The developmental profile shows a progression of increasingly complex motor skills:
- Basic locomotion (running, jumping) → 24-30 months
- Coordinated bilateral movements (catching, stair climbing with alternating feet) → 36 months
- Advanced unilateral balance and motor planning (hopping on one foot repeatedly) → 48 months 1
The presence of hopping on one foot multiple times without losing balance is the definitive skill that places this child at 48 months, as this milestone requires motor maturation beyond what is expected at 30 or 36 months 1.