In his visualization, you can highlight any natural number (the normal numbers we count) on the number line and see how it relates to its fellow numbers.

Aurora Gallardo, The Extension of the Natural-Number Domain to the Integers in the Transition from Arithmetic to Algebra, Educational Studies in Mathematics, Vol. 49, No. 2 (2002), pp. 171-192 ...

An animated journey into the world of rational numbers! A fraction thief disrupts a number town, leading to a fun exploration of fractions, natural numbers, and mathematical concepts.