Cardboard box

We did it with the previous dog, Omo, and now do it with Caspar: we make him have fun!
We hide one or more treats in paper or cardboard, if available a cardboard box, and then give it to the dog. What then happens might be very familiar to all dog owners: the paper/box is shredded. And the treat(s) found and eaten, of course.
It is a big joy for the dog. Cleaning up the shreds is not too much work, so why not?
Today Caspar at first didn't know what to do with the box, until he saw D. put a treat in it. Then it was clear. At first he tried to get to the treats in the middle of the room, but then took the box to his bed, where it's not so slippery.