What I've found on the net indicates compulsory attendance until the age of 18 in Oklahoma with potential juvenile court involvement for those who fail to maintain attendance.
Here's the law (I pulled out the interesting info):
§70-10-105.
A. It shall be unlawful for a parent, guardian, or other person
having custody of a child who is over the age of five (5) years, and
under the age of eighteen (18) years, to neglect or refuse to cause
or compel such child to attend and comply with the rules of some
public, private or other school, unless other means of education are
provided for the full term the schools of the district are in session
or the child is excused as provided in this section.
B. It shall be unlawful for any child who is over the age of
sixteen (16) years and under the age of eighteen (18) years, and who
has not finished four (4) years of high school work, to neglect or
refuse to attend and comply with the rules of some public, private or
other school, or receive an education by other means for the full
term the schools of the district are in session.
Provided, that this section shall not apply:
1. If any such child is prevented from attending school by
reason of mental or physical disability, to be determined by the
board of education of the district upon a certificate of the school
physician or public health physician, or, if no such physician is
available, a duly licensed and practicing physician;
2. If any such child is excused from attendance at school, due
to an emergency, by the principal teacher of the school in which such
child is enrolled, at the request of the parent, guardian, custodian
or other person having control of such child;
3. If any such child who has attained his or her sixteenth
birthday is excused from attending school by written, joint agreement
between:
a. the school administrator of the school district where
the child attends school, and
b. the parent, guardian or custodian of the child.
Provided, further, that no child shall be excused from
attending school by such joint agreement between a
school administrator and the parent, guardian or
custodian of the child unless and until it has been
determined that such action is for the best interest of
the child and/or the community, and that said child
shall thereafter be under the supervision of the
parent, guardian or custodian until the child has
reached the age of eighteen (18) years; or
4. If any such child is excused pursuant to subsection C of this
section.
D. It shall be the duty of the attendance officer to enforce the
provisions of this section. Any parent, guardian, custodian, child
or other person violating any of the provisions of this section, upon
conviction, shall be guilty of a misdemeanor, and shall be punished
by a fine of not less than Five Dollars ($5.00) nor more than Twenty-
five Dollars ($25.00) for the first offense, not less than Ten
Dollars ($10.00) nor more than Fifty Dollars ($50.00) for the second
offense, and not less than Twenty-five Dollars ($25.00) nor more than
One Hundred Dollars ($100.00) for each subsequent offense. Each day
the child remains out of school after the oral and documented or
written warning has been given to the parent, guardian, custodian,
child or other person or the child has been ordered to school by the
juvenile court may constitute a separate offense. At the trial of
any person charged with violating the provisions of this section, the
attendance records of the child or ward may be presented in court by
any authorized employee of the school district.