In short
Daydreaming, losing things, missing details, trouble finishing. Often quiet, so it is easy to overlook.
Constant movement, talking a lot, interrupting, acting before thinking.
A mix of both. This is the most common presentation in children.
Start with your family doctor or pediatrician.
A psychologist or psychiatrist can assess ADHD.
Bring notes from school and home to give the full picture.
Routines, coaching, therapy and, where suitable, medication.