Don't start off explaining what TS is. Tell the (kids) to NOT blink. As they are staring at you, wide-eyed, ask them if they can feel how itchy their eyes are, how dry they are getting, how they have that urge to blink, and how that urge is building and building, and how they feel like they will explode if they don't blink! Do this slowly, then let them blink, but tell them, they can only blink once. They will realize that it is very hard. Then tell them it's okay to be themselves, again. They'll start to blink furiously for a few minutes (because their eyes are dry). Let them know that this is natural, too.
This is what a tic is like. It's a build-up. It can sometimes be controlled for a brief time, but it absolutely must be done, just like everyone HAS to blink! and just like when they were released, it often must be done alot! then tell them, that thinking about blinking, will make them do it alot for the rest of the day. This also happens with TS... thinking about tics, can make them happen, sometimes.
Then explain that tics are something that people who have TS, must do. Tics might be sounds, or movements, then maybe give an example of a few including an obvious one or two that your (student) has. Don't point them out, just mention them in your list of tics.
Sometimes we get a song or commercial jingle "stuck in our head". and we repeat it over and over again. So ask if anyone has had that experience. When you get raised hands, ask them if they were writing in their journals sometime, and used the same word a bunch of times, like "cool". "It was so cool to see the animals, and I thought the lion was way cool, and the zoo was alot of fun and cool." Or maybe the word you could use is "like" (think of the Valley Girls! lol) "Like that is just so, like cool!" lol
We call this "looping". Most people can get unstuck by thinking of another song, or another word. People who have OCD can't, even when they do think of something else, they still are stuck. sometimes they count, sometimes they have to touch things, or adjust their clothing so many times, wash their hands alot or comb their hair, make sure everything is perfect or perfectly even ... (add some your student may have, again without pointing him/her out). Sometimes they have to do this until it "feels right", or else it's like having one shoe tied tight, and the other so loose you're sure it will fall off ... it just feels strange, and uncomfortable.
Another exercise, is to give the kids apiece of paper, and have "Mary had a little lamb" the whole thing, written on the board. Divide the studnets into 2 groups. Tell the one half, that everytime they write the letter "a", they have to scratch it out, and do it again, then scratch it out and write it all over again from the beginning. The other half is to write every second word, twice. At your mark, begin. after 30 or 45 seconds, tell them that their time is up.
Ask them how many had enough time to finish? This is what often happens with someone who has OCD, and is trying to keep up. Sometimes it's impossible!
If (s)he has one of those OCD's where he has to be the last to touch ... tell them that the best way to resolve it... where everyone is equal... is to shake hands!
Sometimes with these things, more common with OCD than with the others, but if these things are not done... you feel very frustrated.
Now have a couple of clear cups, one has a 1/4 cup water... one is half full, one is 3/4 cups full. For EACH of these, have another glass that is 1/2 full of water. (maybe with orange Kool-aid? or food colour) (have a tray for under it, bring paper towels).
Get one of the students to come up and do this for you, but hand it to them as you go.
Everyone has stresses. Some people never seem to get angry, that's because they start off with only "this" much (use the 1/4 cup filled), and when they have a bad day (show the red stuff, then hand to your volunteer to add to the cup), or even a week, they still have room to spare before they get angry (there's still room in the cup).
Most people have about an average amount of stress (1/2 cup), so when they have a bad day (add the red stuff), well, sometimes it overflows, and they get really mad, but they can control it, most times it just gets close, but doesn't overflow.
Those who have TS and other stuff too, well, they're already starting off with a a lot ... (show the 3/4 cup), and when you add the bad day (add the red stuff!), it quickly explodes! It makes a huge mess, and you can't stop it on your own. That's when you need the help of others ... Use the papertowels to help clean it up, and to help clean up your volunteer! lol
This is called a rage disorder. Those who have it, explode, even when you think there's no reason to. The reason could be because they were already full, and that "little thing" was all that was needed to cause the explosion. NOW you can explain that this is what happens to your (TS) student. Maybe sometimes it's because (s)he's looping, or because his/her tics are hurting, and yes, they can hurt! (ask the kids to tap their fingers on the desk for 2 minutes... they'll catch on REAL quick!) lol Maybe (s)he's frustrated because (s)he can't stay focused that day, and instead of teasing him, they can maybe touch his/her paper or his desk to remind him, or whatever else has been agreed on with the teacher, principal, and your TS Student. Maybe that makes it harder for him, and he/she has another idea of what works for them. Ask.