I have been priviledged to use my horse several times as a lesson horse. There are many people who know Precious that might find it astounding that I use her for lessons, but you couldn't ask for a better lesson horse. She is safe, responsive, willing AND doesn't just always do everything asked, she will challenge the rider slowly, when they are ready for it, improving the learning curve, but never more than they can handle.
But beginners don't get access to her mouth. I worked very hard to make her soft in the bridle and response to all of the aids and she doesn't deserve to have inexperienced hands tugging at her mouth. Her bit of choice is a myler version of a mullen mouth pellum, which includes a small amount of leverage (although we don't tighten the curb chain), so I am always careful about who touches the reins attached to it.
Instead I will students a rope halter or a bosol. More and more I prefer a rope halter and it bothers the horses less than the leather of the bosol (I do not use a traditional cowboy rawhide bosol, instead I use traditional Paso Fino tack which looks basically like a leather halter with two rings under the chin for attaching reins. I use a plain noseband without any heavy equipment.
Precious hates the bosol. Once I started paying attention to the different types of pressure it was very aparent that she MUCH disliked nose pressure. She is so happy to ride with her bit in but even a few minutes in the bosol will have her showing unhappiness (and yes, this horse can be occasionally happy).
Well, after a year I let Juliana use the reins with the bit attached. Last night they were such a beautiful picture and I was really proud of Juliana because she had the perfect contact without pulling or letting her reins be too free. It takes time to earn the priviledge of the bit and especially of a horse who responds to it.