Finding things to deal with trich in public are harder than finding things that work at home, but there are some things you can try! I always wear some kind of jewelry I can play with in my hands instead of touching my hair - fiddling with a bracelet under a desk works well, and no one will notice. Or use whatever you have available to fiddle with in your hands - pens, pencils, anything at all.
Some people find that putting something scented, like lotion or perfume, on their wrists makes them notice when their hands go near their hair so they can stop themselves from pulling.
You can also try wearing band aids on your fingers to stop yourself from pulling. If anyone asks about it, just say you are doing it to stop yourself from biting your nails. I hope that helps!

As a teacher, I can tell you that if a student says they need to hold something in their hands because of a medical condition and has a doctor's note about it, there should be no problem with you doing that. Even without a note, most teachers would likely be understanding even if you don't choose to tell them any details about what medical condition it is.

thanks mandapanda!

I agree with Manda, most teachers should be understanding, especially as there is more awareness about these types of disorders now. Fiddle toys such as the "tangle" are great (you can buy it on ebay amazon etc). And there's types of jewellery specifically designed for people with trich. Spinner rings and fiddle bracelets. You can buy them here: http://store.trich.org/Bendable_Snake_Jewelry_s/99.htm for quite affordable prices.

You could get some fun pencil toppers, that's something discrete to play with.

Also I've read about tying some flavoured floss to the top of a pencil/pen, and you can play with this during class.

If a teacher is giving you trouble about being fidgety in class, you can go to a school counselor for help. It may be uncomfortable, but he or she can help explain to your teachers why you need something to hold in your hands. But many fiddle toys are very discreet and very "normal" looking so it should not be a problem.

Great ideas above....
How about purchasing some large animal shaped erasers or other characters, these would be a nice textural feel while holding in your fingers or hand as they are somewhat soft and pliable. Maybe some with beady eyes watching over you so you won't feel the need to pull. I like to intertwine a pencil in my fingers on my pulling hand to keep aware.
Experimenting with many options is the trick to find out what works for you.

I think there might even be fidget pens that you can bend and twist. Check officeplayground.com. I wear prayer beads to fidget with and you know that your teacher couldn't complain about that!

Here's a link that works: http://www.officeplayground.com/