I believe that if you are teaching a class of students, you will want to have a strap for your instrument. Trying to help a student with their playing position, fingering, etc. will be difficult if you are juggling your own instrument at the same time!
There are straps you can get that you do not have to drill holes in your instrument. There's a good overview here at Ukuguides.com. If you want it to be a more permanent solution, however, you can't beat strap buttons. They don't cost a lot to put in at most music stores, but you can also do it even cheaper for yourself. Here's a how-to video for you.