That's not correct. Taking the numbers at face value: out of 100 8th graders, previously 34 were proficient in math. Now 26 are. 23.5% fewer 8th graders are proficient in math. Saying it's an 8% lower number is wrong: the number of 8th graders proficient in math is 23.5% lower. The absolute percentage went down by 8, but who cares?
To illustrate this, consider if 1% of all children were dying of Smallpox, and after the vaccine it dropped to 0%. Did we reduce Smallpox deaths by 1%? No! We eliminated Smallpox deaths; reduced by 100%.
The irony of your statement is left as an exercise for the reader.
> The absolute percentage went down by 8, but who cares?
I do and that's why I wrote it
The only remaining mystery is which semantical variation of that would you and others accept. Fewer? No. Lower? No. Absolutely percentage? Well its not even clear if others would accept that, or find a different way to say you’re ironically dumb.
The purpose of language is to convey a shared concept. Whatever this conversation is has nothing to do with that.
Typically you would say it's a drop of X percentage points, or just "points", or a decrease of Y percent. Using X instead of Y is simply wrong - whether it's wrong mathematically or verbally is philosophical.
This is ironic, considering the title of the article.