(a) A school district may enter into a supplemental agreement with a classroom teacher under which the teacher agrees to perform a duty relating to initial lesson plan design or instructional material selection that is not a duty generally:
(1) anticipated to be performed during the instructional day; and
(2) assigned to all classroom teachers of the same subject and grade level under those teachers’ employment contracts.
(b) A school district may not require a classroom teacher for a foundation curriculum course to spend planning and preparation time to which the teacher is entitled under § 21.404 creating or selecting instructional materials to initially cover the applicable essential knowledge and skills for the course unless the teacher has entered into a supplemental agreement described by Subsection (a). This subsection may not be construed to prohibit a classroom teacher from choosing to spend the teacher’s planning and preparation time creating or selecting instructional materials.

(c) A supplemental agreement between a school district and a classroom teacher described by Subsection (a) under which a teacher is assigned responsibility for a greater number of duties unrelated to providing instruction than other full-time teachers of the same grade level in the district must explicitly state each of the teacher’s duties unrelated to providing instruction.