I used to teach on a Private School on the North Coast...and I think we closed early for 1 afternoon only.
The rest of the days were school as normal. Private Schools are not affected, because they are not open for voting.
The public schools close because that's where the voting takes place...I believe.
It's pretty hard not to get caught up in the party atmosphere...what with all the 5 peso beers they give out on the malecon and all...lol.
However, as a teacher, it's annoying to have to adjust your lesson plan, and cram more into the limited time they give you.