Great trust exercise for your horse, yielding from pressure and a new movement to keep the curiosity going. Extra plus is that you can develop this into your riding as well. 

Make sure you are in a place where you both feel calm and safe. Think of the footing so it is soft. 

There are different ways to teach the bowing but everything comes down to your timing and patience. Like I mentioned above this exercise is about trust and it can consist a lot of pressure for some horses, so be gentle. 

You will start off with part 1