Here is a quote from _Teacher's and the Law_, 3rd edition, by
Louis Fischer, et al. Published in 1991 by Longman. (The book
is aimed at K-12 teachers).

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[Question:] Have due process requirements turned classrooms and schools
into courtrooms?

[Answer:] No. When the Supreme Court ruled in Goss that even short-term
suspensions require some modicum of due process, a hue and cry arose
across the land. School administrators, parents, and teachers were
upset and feared that the decision would force school officials to
consult lawyers before they could take any disciplinary measures in
schools. These fears where ill based. Careful reading of Goss and
other cases indicates that the legal requirements are not at all
excessive and that there is no need for lawyers to be at the side of
administrators or teachers. Conscientious educators used fair
procedures long before these cases ever went to court, and their
procedures amply satisfy the law.

On the other hand, oppressive, authoritarian procedures that do not
respect students' rights to know why they are being disciplined and do
not provide opportunities for students to present their defense in a
fair way are crumbling as a result of the application of the
Constitution to the schools. In sum, one may think of the right of due
process as applying to student disciplinary matters on a continuum
represented in the following diagram:

May act without due process:

Trivial or vary minor matters, or emergencies. The latter must be
followed by due process as soon as possible.

Some modicum of due process is necessary:

Disciplinary matters that may lead to short-term suspensions
or entry on the students' record.

Extensive, careful due process is required:

Disciplinary matters that may result in long-term suspension or
expulsion, or in a significant penalty such as a short suspension
during final exams.

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