Just ask them to do i++ and never stop. That is also infinity.
(or in simpler words, imagine you have a table than you put one apple to it, then one again, amd again and again and never stop. And yes, they would also soon understand, that the table needs to be infinitly big)
edit: of course it is about the sum of the process. they should imagine the pile of things or the number if you never stop adding.
Just ask them to do i++ and never stop. That is also infinity.
(or in simpler words, imagine you have a table than you put one apple to it, then one again, amd again and again and never stop. And yes, they would also soon understand, that the table needs to be infinitly big)
edit: of course it is about the sum of the process. they should imagine the pile of things or the number if you never stop adding.