Hypnotists perform on stage and increasingly now, in schools. Many people get
hypnotized to stop smoking or some other bad habit. Hypnotherapy is used in
counseling sessions. Even if the results seem harmless or good, there is much
more to hypnosis than meets the eye.
A hypnotic state, even a very mild one, is a state where critical thinking and judgment are suspended. Therefore, the person in such a state has their mind open to whatever influences want to come in. The mind in this situation is very receptive and malleable. No matter what the intent of the hypnotist may be, the hypnotist is not in total control. Moreover, there can be bad effects from hypnosis on some people, but no one really knows who will suffer this. All hypnosis is a risk.
The hypnotic state is the same as the altered states one goes into in Eastern meditation and in occult "centering." This state is very desired in the occult because occult practitioners (psychics, tarot card readers, mediums, etc.) know that in this state they are more sensitive and receptive to their supposed sources of information and the guidance of their "guides" or other disembodied beings (i.e., fallen angels, though of course, they do not see it this way). All of the popular mediums go into this kind of state to "hear" from the (supposed) dead and recommend it to others as a way to contact their "guides."
Speaking of the "guides," the hypnotic state is the state one is put in or goes into in order to meet one's "guides." This is how this writer was introduced to a spirit guide, via a guided meditation. When I practiced astrology, I would naturally fall into this state while doing the reading (consultation for the client). It is like having your mind in neutral, open to external or alien guidance that is not from God. Spirit guides are fallen angels.
The hypnotic state is not normal, natural, or healthy. See an explanation for some of the possible adverse effects of hypnosis at https://bit.ly/2tbM7UD.
There have been incidents of people becoming depressed, suicidal, or having psychotic breaks or nightmares, as a result of having been hypnotized. Hypnosis affects the mind and often in a negative manner. It can alter a person's psyche and, over time (as in Eastern meditation), the person's worldview. See a former hypnotist's warnings at https://bit.ly/2DgaO6N.
People in a room where a hypnotist is at work but who are not being hypnotized can still fall into a state of hypnosis when it is done on others. Despite advances, there are many things scientists still do not know about the brain and how it functions, so care is needed with any procedure affecting it.
If a hypnotist is coming to your child's school, I highly recommend that you make sure your child is not in the same room where the hypnosis is being done, even if it's in a large auditorium.
Whether for relaxation, counseling, entertainment, or demonstration --- people should not participate.