THat’s the age it sued to be in Texas. Maybe it’s changed.
Apparently it has changed.
Compulsory Attendance
In Texas, children who are 6, or who are younger than 6, but have previously been enrolled in 1st grade, and not yet 18, are required to attend school, unless exempted by law. School employees investigate and report violations of the state compulsory attendance laws. Education Code Sections 25.085 and 25.087 require a person who is 18 or older, and is enrolled in public school, to attend school each day. If a person who is 18 or older and is enrolled in public school has more than five consecutive unexcused absences in one semester, the school district may revoke the person’s enrollment for the remainder of the year. Any student that has been absent for 20 consecutive unexcused school days may be withdrawn from school.
http://www.mckinneyisd.net/parents/attendance/?Id=7