In what circumstances is the right of free expression in schools not absolute?

Freedom of speech is not absolute anywhere. One person's "freedoms" end where another person's freedoms begin.

Check this site:
http://en.wikipedia.org/wiki/Freedom_of_speech

This site specifically talks about freedom of speech in school:

http://www.freedomforum.org/packages/first/curricula/educationforfreedom/supportpages/L08-CaseSummaryTinker.htm

The right of free expression in schools, like any other constitutional right, may not always be absolute and may be subject to certain limitations depending on the circumstances. While students have the right to express themselves and share their opinions, there are some situations in which this right may be restricted or limited. Here are a few circumstances where the right of free expression in schools is typically not absolute:

1. Disruption of the learning environment: Schools may restrict students' free expression if it disrupts the normal functioning of the educational environment. For example, if a student's expression significantly interferes with classroom activities, creates a hostile or unsafe environment, or hampers the rights of other students, the school may impose limitations.

2. Hate speech or bullying: Schools may regulate or prohibit expression that involves hate speech, harassment, or bullying towards others. This is done to ensure a safe and inclusive environment for all students and to prevent the harmful effects of such speech.

3. Obscene or indecent language: Schools may restrict students' use of obscene or indecent language, as it can be disruptive or inappropriate in an educational setting. Determining what qualifies as obscene or indecent may vary depending on the age group, cultural context, and prevailing community standards.

4. Violation of others' rights: Students' free expression may be limited if it infringes upon the rights of others, such as invading someone's privacy, defaming or spreading false information about individuals, or inciting violence.

It is important to note that the specific limitations on free expression in schools can vary depending on the legal framework and policies in different jurisdictions. Understanding the specific rules and regulations established by the school or educational institution is crucial to fully comprehend the limitations on free expression in a particular context.