so why let students break slides? because that's the best way they learn that thick slides cannot be viewed using the highest power objective lens; that you can't adjust coarse focus using the highest power lens; and that you have to judge by the type of specimen what the optimal magnification is
I use this to introduce microscopes to beginning high school students. A side benefit of the slide is that because it is a thick slide, students have cracked the cover slip by not following instructions about adjustment knob use. That is a lesson that they are unlikely to forget, as they are responsible to pay for damages.
Great Slide for Depth of Field -- better than home made!
I teach a light microscope class at my homeschool support group. I used "homemade" crossed thread slides (using nail polish as the "mounting fluid") for a couple of years before buying this one. The improved clarity of the slide is worth it for teaching depth of field and focus!