A boundary is anything that resembles a mat/bed or can be recognized apart from the floor. We teach pups to stay on boundaries for eventual moments when they will need to be stationary for hours  (like an office while their handler works, or a restaurant or classroom). In practical life, it allows a handler to make supper or to keep the dog out of wheelchair lanes in a home. Like everything else, we build the behavior from scratch, then proof it, then take it on the road

The theory is, if we pay them enough, often enough, they will choose to plunk their butts on the boundary. 
You'll start to notice a pattern in our training; reward any interaction, increase expectations, increase duration, distance and distractions. 

Step one is decide on what you want to use for a boundary for teaching this! For the first bit I'll ask that you use the same item so the pup gets used to the game. After a bit, we can shape different things to lay on. And add a cue of "Settle".  The actual "settle" looks like the dog is comfy and laying down with legs out to the side, relaxed. They will understand they will be there for a while. Most dogs do this naturally, my do is sleeping on the sofa beside me right now. No difference, except the Service Dogs will do it everywhere and for as long as the handlers need. 

So get your mat! Place it on the floor, by now our pups will be responding to the word "yes" like a clicker. It means they are doing what we like. Yes + kibble is even more rewarding! 
When the pup explores the new item, yes/kibble. When they are interacting with it (a foot on; yes/kibble. Day one we really just want to start to build a positive association with the boundary! Any interaction gets a yes/kibble

That's it! Practice this until the pup is eagerly interacting and "get it" you'll know, they expect a reaction from you! 

The next few days (5 minute sessions) lets see if we can get the pup to sit on the mat, all of their own choosing! No luring, leash guiding or verbal cues. Simply yes/kibble when they are doing it right. When they are in position, jackpot of food delivered to their mouths. High rate of reward, Once they've had 10-15 kibbles, toss a couple and say "get it". Wait for them to reposition themselves on the mat and jackpot them again. Repeat; the goal is to have a happy puppy bouncing back onto the mat! 

Practice this when you're cooking and need the pup out of the kitchen, reward being on the mat. Practice this when someone comes to the door. When you go to the bathroom, during commercial breaks. While you have a coffee.... all tend to be times that we are able to add the training on, without having to lose time to do so! Training can be done in little bursts (and is actually better in short sessions multiple times a day). Find your spots during your day to practice it. 

Next goal; laying down. So in a natural way, the longer the pup sits on the boundary, the more apt they are to lay down. When they do, jackpot. Remember to deliver the kibbles one at a time and directly to their mouths. If they are popping up, practice the Airplane in hand feeding. 

Duration now that we have the behavior! The pups start to think the boundary is magic, because good things happen there. Lets start elongating that! Lets get them to 5 timed minutes. We build that the same way we build all other behaviors... bits at a time, building on success and understanding. No words! No uh-uhs! Start with 5 seconds, go to 10. Once 10 seconds can be done without a consant stream of kibble move to 15. Build this by 5 second increments to the 1 minute mark, after that you should be able to build 15 second jumps. If at any point the pup is not holding, back up to the previous goal. Getting to 5 minutes is a huge marker! 

Let's now, that the pup fully understands the goal, start really moving the mat around. Back Deck, under the kitchen table, bathroom, beside your bed. Back seat of the car. All rooms, hallways. On the sofa. On the lawn. If you have time, feel free to visit a park and at the outer edge, practice it there too! 

Distance you are from the mat is the next challenge. Start moving one step, then back to treat. 2 steps/treat (always return to the pup on the mat and deliver to mouth). Slowly work up to leaving the room. We want the pups butts glued to the mat. Lower criteria if the pup is vouncing up to follow you!

Distractions! This is where it gets fun. Squeak a toy, bounce a ball (tiny tosses at first), roll a ball. Dance, Sing. Jog in place. Be the nutty neighbor who talks in a high pitched voice and gets puppy excited. Heck invite them over to help proof/encourace the pup to choose the boundary. Sitting on the front lawn with people/cars going by. Near a pasture of cows. Try it everywhere! the more the merrier! We are building solid pups that believe all good things come to them, they don't need to investigae everything. 

Add distance away to distractions and duration. Build the D's one at a time. 

PS Dr Karen Overall has put this together, I think it's worth sharing, it's a terrific break down of when to add movement (away from the boundary or crate) and when to start over.