Well for all ye survivors of batch 19-- (I'm not saying!) I just discovered something about the ruler rule...
My favorite chemistry teacher, Mr. Pulmones, required all of us to use a branded ruler - Orions. He explained that we should use this ruler because it had the most accurate line measurements compared to other rulers. I complied of course. I followed this rule through the years and only bought this brand for my son because of that belief, although at times it crossed my mind that maybe he partly owned the company (haha!).
Anyway, so I was chatting the other day with my friend, Anne, who went to the same school in Bacolod. We've been comparing a lot of notes since we discovered we went to the same school (just different sites). I digress. So the ruler rule came up and I was surprised to find out that they had been required to use the same brand as well. She knew though why it was required. Apparently other rulers because they are opaque provide students the opportunity to cheat coz you can write notes on it (i.e. chemistry formulas!). So that's the real reason why they asked us to use Orions rulers.
Okay, it took more than 2 decades for that belief to be debunked. In any case, I'm still going to use Orions rulers.