Ohio student shot at school gets detention for participating in national school walkout then told..

[Ms. Toad]

48. Actually, they wouldn't, at least as to the detention.

Walking out of class is fundamentally disruptive, and school are permitted to make and enforce rules to minimize the disruption - as long as the rules are not designed to suppress or especially target speech. Assuming the school regularly assign detentions for people who cut class, they are not specifically targeting the speech

The case you are thinking of involved wearing black armbands to school, but did not otherwise interfere with the educational process. in other words they engaged in pure political speech (entitled to the most protection) without interfering with the educational activities.

As to the requested apology, my understanding is that was a suggestion made at an open meeting of the school board, not an obligation actually imposed as punishment. (If it was, it does infringe his free speech rights - specifically, his right against compelled speech.)