It’s been three days now that a very important operation is going on: invisible sand transportation!
The loading takes place at the right side of the coach, where a green (and perfectly visible) truck is being loaded with cargo. Then, it pulls out (very carefully, not to loose a single grain), and goes to a building site (invisible).
Once it reaches the left side, it stops, lowers the loading platform and unloads the sand onto an invisible heap.
– There’s no more left! (A hand gesture.)
All the sand is unloaded, and the truck is empty!
– Look mommy, empty!
– Yes, Leo, empty!
The truck goes back and rushes to the loading site…
And this goes on.