Flash mob in Cuba

I’m not exactly sure what to make of this:

http://english.donga.com/data/20101122/photo/2010112285918.jpg

Hundreds of “flash mob” students lie down and a few stand with their arms open Saturday at a Havana square in Cuba. Wearing T-shirts reading “Join,” they marked the 21st anniversary of the U.N. Convention on the Rights of the Child. A flash mob is a large group of people who suddenly assemble in a public place, perform an unusual act for a brief time, then disperse.