I worked on Puppy Push-ups tonight. You give the command sit then down then sit then down, so on and so forth. I varied the rewards, the first sit they get a treat then they have to sit - down and get a treat. I varied the rewards or my dogs will sit then down, they begin to chain the behaviors because they know what you are going to ask next.
It's a good way to really define a behavior and know that they truly do understand the command. The more you practice the better your dog will become with it's commands. Another benefit is that your dog will learn to be more attentive to you, not just when your training them.
If you want more guidance in dog trainging I recommend getting a copy of The Culture Clash. If you want to work along with us we are on Kindgarten down in the section Nuts & Bolts of Obedience Training.