  The paper describes the practical work for students visually clarifying the
mechanism of the Monte Carlo method applying to approximating the value of Pi.
Considering a traditional quadrant (circular sector) inscribed in a square,
here we demonstrate the original algorithm for generating random points on the
paper: you should arbitrarily tear up a paper blank to small pieces (the first
experiment). By the similar way the second experiment (with a preliminary
staining procedure by bright colors) can be used to prove the quadratic
dependence of the area of a circle on its radius. Manipulations with tearing up
a paper as a random sampling algorithm can be applied for solving other
teaching problems in physics.
