How was まで used in this sentence: やる気がない者に構ってやるのは義務教育まで


I was wondering how まで was used in this sentence:

> やる気がない者に 構ってやるのは 義務教育まで→ 意志なき者は去るほかない




It's a particle that means "until ～". 義務教育まで just means "until compulsory
education".

> やる気がない者に構ってやるのは義務教育まで(だ)。  
>  It's only until compulsory education that I care about people who aren't
> willing to do it.

If you still have trouble parsing this sentence, check the [grammar of cleft
sentences](https://japanese.stackexchange.com/a/19208/5010) (aka ～のは～だ
construction).

