Instead, why not stimulate your child’s imagination? Bring up the fact that Job lived long before telescopes and spaceships.
فَكَيْفَ تُظْهِرُ لَهُ أَنَّ هٰذِهِ ٱلْآيَةَ كُتِبَتْ بِوَحْيٍ مِنَ ٱللهِ ؟‏