In questo articolo dimostriamo l'esistenza di curve "buone e generali" di grado $d$ e genere $g$ che giacciono su di una superfice liscia di grado $s$, per ogni $s\ge 4$, $d\ge \left(\begin{array}{c}s\\ 2\end{array}\right)$, e $g$ in un certo intervallo vicino al genere massimo.

The article presents some possibilities to create non-convex star polygons from regular polygons. The text includes exercises about the construction of the star polygons and exercises inciting to study their attributes and their using in the everyday life of the pupil. The subject of the star polygons deepens the basic curriculum in plane geometry in RVP and it is a suitable motivation complement in teaching mathematics at the second stage of elementary school as well as at grammar school.