This experiment demonstrates atmospheric pressure and superficial tension.
When carrying out this experiment, we suggest it is done at a sink or outside.

A glass
Some water
A piece of glossy paper / laminated paper / post card.

Fill your glass with water, and cover with the piece of paper (as in the drawing).

Experiment 6:

What is superficial tension?

Hold the paper on the top of the glass and quickly turn over then remove your hand.

The explanation given in most science books is : The atmospheric pressure causes the paper to stick to the glass keeping the water inside.
In fact, there is another phenomenon which intervenes to hold the water, and prevents the paper from falling: it is what the physicists call superficial tension. It is thanks to this force, that the paper remains stuck on the surface of the water.

Surprise: the water does not pour out.