Before the puppies left we tried them on the the clam shell bottle challenge. It's a fun test of their willingness to put up with the noisy bottles being pushed around. (Actually, we had trouble finding enough bottles, so there are some milk cartons there too.)
Kay only put in a handful of kibble, so perhaps the motivation wasn't as high as if it there had been hot dogs. However, Humphrey was straight in and while his litter mates watched in fascination... he scoffed the lot!
The next day we tried it again and everyone got in without much hesitation... they weren't going to let Humphrey eat it all for a second time!