The short answer is yes, they do. If a student is in general education or  “may be” participating in general education, a teacher needs to be there.

Note that general education teachers can be excused from the meeting if the parent consents in writing and the teacher provides written input for the meeting. AKA they cannot just not show up.

What IDEA says about the general education teacher in 34 C.F.R. § 300.321(a)(2):

Not less than one regular education teacher of the child (if the child is, or may be, participating in the regular education environment);

What IDEA says about excusals from the meeting in 34 C.F.R. § 300.321(e):

(e) IEP Team attendance.

(1) A member of the IEP Team described in paragraphs (a)(2) through (a)(5) of this section is not required to attend an IEP Team meeting, in whole or in part, if the parent of a child with a disability and the public agency agree, in writing, that the attendance of the member is not necessary because the member’s area of the curriculum or related services is not being modified or discussed in the meeting.

(2) A member of the IEP Team described in paragraph (e)(1) of this section may be excused from attending an IEP Team meeting, in whole or in part, when the meeting involves a modification to or discussion of the member’s area of the curriculum or related services, if—

(i) The parent, in writing, and the public agency consent to the excusal; and

(ii) The member submits, in writing to the parent and the IEP Team, input into the development of the IEP prior to the meeting.

The short answer is, participate. The longer answer from IDEA is to speak to behaviors, supports, and strategies that work for the student in their class or where they see a student struggling. If the student is not in their class (in the “may” enter general education bucket), the teacher can speak to the work and behavior expectations in their class.

What IDEA says about the general educator’s role in 34 C.F.R. § 300.324(a)(3):

(3) Requirement with respect to regular education teacher. A regular education teacher of a child with a disability, as a member of the IEP Team, must, to the extent appropriate, participate in the development of the IEP of the child, including the determination of—

(i) Appropriate positive behavioral interventions and supports and other strategies for the child; and

(ii) Supplementary aids and services, program modifications, and support for school personnel consistent with §300.320(a)(4).

Most often, general education teachers just share how a student is doing in their class and the challenges and successes they see.

However, general educators have unique knowledge into what accommodations are working, not working, or missing — and unique knowledge into the needs of the student in a general education setting. 

That means that they can and should help shape the accommodations and goals of the IEP. It rarely happens– but that is the dream.