A very significant new publication aimed at the younger horn player (and their teachers) is Preparatory Kopprasch by Jeffrey Agrell.
What Agrell has done is take the familiar Kopprasch melodies and reduce the range and simplify overall, creating a wonderful option for working with younger students. If you teach younger students I think you will find this publication to be a breath of fresh air.
Agrell did make some choices. Besides reducing the range (only touching the top of the staff toward the end of the book), I think among the more obvious ones is he has removed all dynamics and there are no short articulations presented in any etude. With the standard Kopprasch book those are two of the key elements to study — mastering clear dynamic contrasts and also crisp articulations — and the choice to remove them make sense in that you can work on those things later. And, of course, you have complete freedom as a teacher to write in dynamics or different articulations as you wish.
Nicely printed and bound, presently priced VERY affordably at $9.99, Preparatory Kopprasch is part of his Millennium Kopprasch Series. It may be purchased on Amazon here.