Hi mastesrJaime I have a question?
I'm teaching vocal lessons to a young guy that is 16 years old, and He heared from some school teacher, that warming up with full octave it's harming for his voice, he is right or just it's a believe about that?
thanks so much bye bye

Well in my experience it depends on his range and where he's at. I wouldn't recommend doing scales without proper placement because that's how I blew out my voice twice. Plus it often takes like a good 20-90 minutes to get warmed up in chest and head voice.

Scales are great tools for teachers to assess and beginners to learn notation. The problem often occurs when a student without proper placement and lack of practice then begins scales and tries to force his voice and keep up with the teacher who cheers them on to go higher (and often faster).

If it's a new student they would probably benefit more from practicing falsetto/head voice and hitting random notes (in their range). Otherwise with just scales you can already wear them out (and spend a lot of time before any signing actually begins).

Greetings Em,
It is good to see that you want to help, it is also good to see that you ask for answers when you do not know them.

The answer has a dependency - if the boy is warming up with proper vocal technique and a properly structured warm-up then he should be able to sing in his whole range very comfortably during warm-ups - which may contain many octaves. If the boy is not using good vocal technique then any vocalization can potentially harm his voice because of tension and strain.
ALSO- If you are referring to the Siren exercise (sliding a full octave) remember Jaime's instruction to work UP TO the full octave at first, because proper technique, strengthening and coordination are required for a nice, smooth, connected slide. This is also the last exercise you should introduce after working steadily for weeks on Falsetto Slides, then 2 weeks on Transcending Tones. Follow the routine guideline on page 255. Even if you do not utilize the time guideline, dedicate the equivalent amount of time to each exercise, do not move on until you understand what you are doing and you are doing it with proper technique. Quality - not speed - is most important. If he does not understand and use proper technique for Falsetto Slide then do not move on to Transcending Tones. Transcending Tones begins with a proper falsetto - if he cannot do a proper falsetto, then he can not properly begin a Transcending Tone.

Very closely study Part One and Part Three of the book - Part One is Technique, Part Three is how to apply the technique to the exercises for proper use and results. He must have a full understanding of the ideas and feel all of the mentioned "buzzes" to know he is using the technique correctly, and doing the exercises correctly.

ALSO REMEMBER - Falsetto Slides, Transcending Tones and Sirens are not ACTUALLY Warm-Ups, they are Exercises. They are meant as "sit-ups and push-ups" for the voice to make it stronger and get it coordinated. Warm-Ups are more like stretches for a dancer or runner that prepare them. So it is advisable to do warm-ups BEFORE your exercises. For Warm-Ups check out Jaime's "Ultimate Vocal Warm-up" Audio - it goes perfectly with Raise Your Voice 2nd Edition.