It just hangs vertically, doesn't move towards the "blown" side despite air moving over one side faster.
Indeed, the paper trick is a little misplaced. The driver is the curvature of the paper (think boat sails), which exists when blowing horizontally, and leads to a momentum change (force which is the lift) ... but not if the paper hangs vertically.
For those who have never heard of circulation and Prandtl (and that is 99 % or more of pilots), the first video in Vessbot's post #16 is of a 16 mm film taken of a water tank experiment by Prandtl in 1929. He, and his students, had been working on getting a flow visualisation of the circulation starting/stopping vortices which they knew, theoretically, existed. They experimented with several types of particles to achieve the reflective record - one was just small flakes of aluminium. A neat sideline in the video is that the Reynold's Number suits the formation of Karman (or von Karman) vortex streets - the oscillating vortices in the wake. To demonstrate the small, incestuous nature of aviation, von Karman was one of Prandtl's academic students ...
Providing you don't want to get too involved in the sums (David, and the link to which he referred, can do that sort of stuff for us much easier then we can) the basic circulation model concepts are very easily explained and understood. I use them for my theory class students and no-one seems to have any great problem. However, due to the poor communications in the early days of aviation (when there was not much academic interest) all the enthusiast guesses as to what was going on led to all sorts of half baked ideas which became entrenched in subsequent pilot training. Think about it .. folks still prattle on about Coanda (which is of little relevance) and Bernoulli (his stuff is fine, but used rather out of place to try and explain aspects of lift) when physicists and engineers have been using the circulation model for a CENTURY to work out flow numbers.
Is it any wonder, then, that thousands upon thousands of pilots are totally confused about lift and lifting surfaces ? As a great little tee shirt, given to me last Christmas by a grandson, has it, lift is all about magic. Different bits of the aeroplane have different contributing magical qualities .... and not a word about circulation, Prandtl or fact-based simple explanations.