I think you're misunderstanding what this person meant.

They're not talking about teaching high level engineering.

They're talking about teaching math in a way that isn't abstract.

Introducing mathematical concepts that can be used to solve specific challenges.

Anchor it in something that makes sense.

Find the slope of this line for no reason at all because I'm the teacher and fuck you, versus build something out of popsicle sticks that will make this ball roll into the hole. The slope is too steep the ball goes too fast and misses the hole. It's not steep enough and the ball stops.

Or whatever. It doesn't need be university level engineering to be engineering.

I hated math as a child. I tried to upgrade my high school math as an adult and I could finally articulate why I couldn't do math. The teacher isn't there to answer questions. They're not there to engage with the subject matter. Math teachers do not teach math.

They read some shit out of a book and you teach yourself math. This is fine if you're innately interested in the subject matter and fine with how impractical and abstract math is, but for the vast majority of people they lack the interest in the subject matter that would drive someone to do well in it, the ability to intuitively grasp the concepts let alone apply them, and they clock very quickly how fucking pointless the entire exercise is.

Changed it how?