My son's teacher wanted a wooden ruler without holes, which is almost impossible to find. I ordered them because they looked like they would fill the bill. I only need one for my son which leaves me an extra 35. I also teach so they will probably be used in my class. One benefit for me is that they have a recessed center that can work very well for the lab marble energy transfer that my students are doing. Full Disclosure: One of the 36 has a tear on one end that I could fix with glue, but it could also break. I think the split was due to the metal edge tucking into the edge of the ruler. Given that abstracts are only 50 cents each, I'm not going to get too carried away with this. The markings are very dark and therefore easy to read. For 50 cents a piece I think it's a good buy.