Developmental Milestones

Some age-related development periods and examples of defined intervals are: 

• newborn (ages 0–5 weeks); 
• infant (ages 5 weeks – 2 years); 
• toddler (ages 3-4 years), 
• play ager/Grade schooler (ages 5–12); 
• Early adolescent (ages 13–15), 
• Late adolescent (ages 16-19).

https://en.wikipedia.org/wiki/Child_development_stages

https://www.cdc.gov/ncbddd/actearly/milestones/index.html

https://www.cdc.gov/ncbddd/actearly/milestones/milestones-in-action.html