I’ve been thinking about this a lot lately.
Newborn 0-3 mo
Infant 3-6 mo
Baby 6-12 mo
(Parents are always tired)
Toddler: 1-3 yrs
Pre-schooler: 3-5 yrs
(Parents are always late)
Grade-schooler: 5-13 yrs
Teenager: 13-20
(Parents are apparently always wrong)