A geometric derivation of Noether's theorem

Noether's theorem is a cornerstone of analytical mechanics, making the link between symmetries and conserved quantities. In this article, I propose a simple, geometric derivation of this theorem that circumvents the usual difficulties that a student of this field usually encounters. The derivation is based on the direct use of the differential form $pdq -Hdt$, where $p$ is the momentum and $H$ the Hamiltonian, integrated over a simple curve.