  Teaching modern physics in high school is of increasingly importance as it
can offer students a more realistic and updated vision of the world, and can
provide an opportunity to understand the most recent scientific discoveries. In
this context, General Relativity (GR) occupies a prominent place, since it is
related to astonishing scientific results, such as the first image of a black
hole or the discovery of gravitational waves. In this paper we describe an
educational proposal aimed at teaching GR in high school in a fun and playful
way using the so-called rubber sheet analogy. We present a set of instructions
to build a simple and low-cost space-time simulator, and a series of related
educational cards that guide the teacher in the implementation of the
activities step by step. This work is the result of a long and productive
debate among Italian high school teachers who collaborate since many years with
the Department of Mathematics and Physics of Roma Tre University in Rome. As
our proposal relies on the collaboration with the final users, we believe that
it will meet their needs and expectations, and it will help to treat GR in high
school more and more over time.
