“…Between the ideas that come into play when students face tasks involving the notion of infinity, we find that the youngest students, or those who have not studied much mathematics, tend to display uncertainty or resistance towards the possibility of the existence of infinite collections (Juan et al, 2012;Montoro, 2005), or they tend to consider infinity as indefinite (Belmonte & Sierra, 2011). Two very deep-rooted finitist visions are to conceive infinity as a very large number or to extend the property of finite sets to infinite sets (Juan et al, 2012;Monaghan, 2001;Montoro, Scheuer, & Pérez-Echeverría, 2016;Waldegg, 1993). Young people very often conceive infinity in potential form (Arrigo & D'Amore, 2004;Fischbein, Tirosh, & Hess, 1979;Monaghan, 2001), and for a minority of university students it is conceived as actual infinity (Montoro, 2005;Moreno-Armella & Waldegg, 1991).…”