In dog training, when it comes to teaching your dog behaviors, remember it is the reinforcement history that a behavior has that builds value and strength of that behavior. With that in mind this dog sit challenge practices a lot of repetitions of your dog sitting in a quick amount of time. How many times in a minute can you ask your dog to sit? See if you can do at least 8 times. Here are two videos of playing this with dogs, one using a clicker and the other using a verbal marker.
As always, have fun!