To help beat the winter doldrums, I bought Kendall one of Nina Ottosson's interactive dog toys.
I chose the one called Dog Fighter because it looked a little more difficult than some of the others, and I was able to find it in wood. It consists of seven slots into which you place large pegs. The pegs have hollowed out places to hide dog treats. The peg only fits in one end of the slot, then you slide it to the other end. To get to the treat, the dog has to slide the peg and knock it out of the slot.
We play the shell game with Kendall using plastic picnic cups. I introduced her to the game by substituting the pegs from the interactive toy for the plastic cups. That way she knew to expect a treat under them. Then I put them in the slots and let her figure it out. It didn't take long.
Here's a short video of her playing the game. This video is also on YouTube where it might be a bit easier to view. Here you have to wait for it to buffer.
My co-worker, who also has a Cavalier, bought a couple of puzzles, too. We're hoping to switch puzzles at some point to keep them engaged and curious.