I’ve just retired from my second career, teaching engineering topics in a high school.
The average incoming freshman cannot read 1/16” on a standard student ruler, and don’t even think about calculating a radius for a hole 2 1/8” diameter.
On the other hand, they seem to have terrific self esteem.
This says it all. The killer technique that schools use is simply to ignore stuff that 50 years ago was routinely taught. The basic foundational stuff that you need to keep going further is deleted.