Level 1: At the beach collect a spoonful of sand. Count how many grains of sand are in a spoonful.
Count how many spoons of sand it takes to fill you plastic container. Work out how many grains of sand that will be.
Level 2: Using you plastic container, dig the deepest hole in the sand that you can, down to the water line (where the water starts filling the bottom of the hole). Count how many container loads it takes to dig you hole.Work out how many grains of sand that is.
Level 3: Calculate the rough dimensions to the area of the sand (from the water's edge, to the top of the beach and down to the water line), using the number of grains of sand in you hole, see if you can calculate the number of grains of sand on the beach. (And to think God could tell you the 'serial number' of each grain - worldwide - and tell you where it originated and travelled in its 'lifetime'.)