Beg or Sit Pretty
This exercise is a tough one to teach at first, every dog being different on how quickly they work it out. If they aren't strong enough in their core, then maybe wait until they've worked the rest of the exercises for a while and come back.
I have always taught it by having them in a sit, and then asking for a paw. Then I lure them up on to their back end, while supporting them a bit with that one leg. The issue with this way, is that some dogs rely on leaning on you. I quickly try to hold them a bit less and mark when I feel they are doing it but still for some they think they can just lean and never try on their own. I talk about some other ways you can teach it, on the video.
Really, it's about the dogs finding their balance point and where to have their front feet to maintain it.
What is this working?
Really works on their core muscles.
How many reps?
Build up to holding longer. Eventually up to 10 secs but that's a long term goal. 5 reps of it, at whatever level of hold they can manage.
How to make this more advanced?
Once they are super at it, you can get them doing it on balance things. Like on a peanut or upside down Bosu. These are very hard though and well down the track. Good form on the flat first! I show how doing it on a board will help the dogs who want to stick feet out and don't have good form. You can also make this harder by teaching them to wave in that position or hold something in their front feet.
When they get really strong you can ask them to go from the beg in to a tall position, assisted and first and then unassisted.