"if your child is in school full time, and is under the age of 24 for at least five months" is misstated.
It should read if your child is in school full time, for at least five months, and is under the age of 24 (at the end of the year), they qualify as a qualifying child dependent. dependent.
The five month rule applies only to being a full time student, not the student's age. The student must be under 24 the whole year.
