Dividng walls/collapsible walls?

I was watching a TV show once, not Extreme Home Makeover, but something where they were showing do-it-yourself projects on a tight budget and one thing they did was add some walls to divide a kids room into two rooms. The walls they used were some sort of temporary wall-like they didn't build a full on wall--the wall could be removed--but it looked like a regular wall. Does anyone know what these are called and where to find them?