Growing up, I my schools never made any kind of observance about day 100. My kids go to different schools and each school makes a big deal out of it now, and they're schools near where I used to attend.

A typical school year is 180 days, why did they start making a big deal out of 100 days? It's past the half point, which I think would be more of a milestone than some arbitrary number picked out because it happens to be the first third digit day.