Here is the relevant code from Maryland law about health Ed only:
Sec. 13a.04.18.01. Comprehensive Health Education Instructional Programs for Grades Prekindergarten—12
(e) Student Opt-Out.
(i) The local school system shall establish policies, guidelines, and/or procedures for student opt-out regarding instruction related to family life and human sexuality objectives.
(ii) For students opting out of family life and human sexuality instruction, each school shall establish a procedure for providing a student with appropriate alternative learning activities and/or assessments in health education.
(iii) Each school shall make arrangements to permit students opting out of the objectives related to family life and human sexuality to receive instruction concerning menstruation.
(iv) The local school system shall provide an opportunity for parents/guardians to view instructional materials to be used in the teaching of family life and human sexuality objectives.