crow-hopping horse dont know what to do to correct

Just a thought, but could his back hurt?  Perhaps his saddle doesn't fit and having little kids bouncing around on his back at a faster gait hurts?  Could be that he's learned that a little humping of his back gets the little ones to back off

i think it probably is soreness but I'm not the one that is in charge of what horses can and cant be used my boss and after this lesson she him from the lesson board so he can rest. It could be that he doesnt like someone bouncing around on his back when he is sore could be but this particular little one has good balance, a good seat, and does not bounce much. He is the type of horse that he wont go faster trot or lope/canter unless you know what your doing i can get him to go but others cant and little kids cant so they sometimes have to pick up the reins to get him to go.
All i know is that he isn't suppose to do that sort of thing with little kids and he is not going to be used for a while so he can rest i know that.
But how can i correct it the crow-hopping from the ground when the lesson is going?

Sorry.  I think crow hopping is a blast!  Your good-seated student is getting some good practice!  I think they try that to test the rider.  I don't think it will last long if the rider works through it.  It's a learning experience!

crow hopping is fun but its not so much fun when he starts crow hopping on kids that do not have a good seat which he has done. Its good that he crow hopped with the rider that has the good seat this time.

What do you do to stop it when the horse does it?  If you can see it coming (ummm, I think that's what you said) why not ask the student to do the same thing?  Is that possible?

Well, if you could work him with an experienced rider first and maybe use a lunge whip so when you see it coming, you could snap the whip at him and get him to realize you don't want that behavior.  Make him hustle (until he's puffing a little) whenever he decides to crow hop so then next time he thinks about it, he remembers he had to work harder when he did that.  This worked really well w/ a horse I had that didn't want to stand for the farrier.
 
If it is a pain issue though, that wouldn't solve the problem.  If he's older and has a bony back, even though you don't choose the saddle, maybe you could throw an extra pad in there so the little ones aren't bouncing on his spine so much?  One of our geldings is very sensitive to having the fenders touch his loins when being ridden western at the trot/canter.  By adding a smaller foam pad that lifts the saddle off, he doesn't crow hop.
 
I'm glad his owner took him out of the lesson string.  Insurance-wise, you just can't have a horse that might dump someone's child, especially if there is proof he has done this before and you guys knew about it.

he was sore. we had to have adult riders on him for a trail ride and he is older so it caused him to get sore. he only crow hops when he is sore and we have to tap him with the reins or saddle string. he doesnt like that but he wont listen to the students legs or voice but they go through asking the horse to go with all their natural aids before they use the reins or saddle strings. i have no problem getting him to go. so its harder for me to understand why they are having such a hard time getting him to move out.

Ok, let me think here, you put the horse on break, he crow hops when he is sore, but you want to know what to do to correct the crow-hopping when he has a rider.  The logical explanation is to not use him for lessons when he is sore.  I have lesson horses and I know that sometimes they have to work through it, but I have found it a very good investment to ensure the health of my lesson horses to buy them decent tack that fits horse and rider and you may want to make a pros and cons case for your boss.
 
I'm sure you are larger and more stable than the kids you are referring to.  You can support your own balance, so it is easier for the horse to move forward.  Kids, even very small kids, can throw the horse off terribly if they are relying on the horse to keep the balance for the pair.  An adult is even worse if they are off balance because of the weight factor.  I have one adult that I teach that had a very poor physical fitness level when she started.  I hated putting her on my horses because I could guarantee that any horse would be sore after she rode, even with good fitting tack.  I gave her lots of at home exercises to do, and with that she took the initiative to start running, go to the gym, and take the responsibility to work between her lessons.  She's still learning, but her dedication has greatly relieved the stress on my horses.  I always give the kids "homework" to let them keep their bodies riding ready between lessons.  This helps build their core strength and will allow them to balance themselves better when they get on the horse.  Also, show them how to use their bodies best to give them the most strength.  I find that teaching kids to look for a change in gait rather than speed helps a lot.  When they look for speed, they naturally push the horse on the forehand, making it harder for the horse to move forward and make transitions.
 
Older horses are often stiff or weaker, depending on what they did through their lives.  We tend to rely on their "been there, done that" attitude, but we also forget about their fragile state.
 
We all have to work hard, and often times we have to work through discomfort, but I do try to minimize that discomfort for my schoolies by offering them decent tack and teaching even the smallest riders how to look for their balance first.  If you can tell when he is going to do it before he does it, then stop it before it happens.  Teach him a solid "whoa" command.  I can stop any of my schoolies by my voice from any gait and this is an invaluable tool.  Also, don't ignore what he is telling you or it will turn into a scream from him or lameness if he learns to stay quiet about it.
 
Remember that to fix a problem, don't look at the problem, look at the source.

If im ridding him i usually push him through it and make the horse do what he is supposed to do correctly without crow hopping, i only have to get after him once and he wont crow hop again. but i can only do that from on him and its kinda hard to explain but i may ask my boss how i can teach someone to correct it when he crow hops but the rider is a intermediate beginner for lack of better terms. she isn't really a beginner but not quite to the intermediate riding stage. so i am not sure she could correct him properly