This question of "what skills are students missing?" reminds me of the new teaching methods they were trying out as I started high school. The new teaching program centered around objectives. The idea was that each objective was a skill that the student needed to learn, but the upshot was that you had to score more than 70% on every single quiz to pass the class, and that you could retake every quiz you failed, repeatedly.
The implementation varied between classes - in my World History class, there were a large number of objectives, and each objective was met by a small quiz that tested ~one skill. (There were a lot of retaken quizzes in that class.) In Biology, there were about 10 objectives for the entire semester, so you could still pass while missing a few small skills, as long as those missing skills were spread out among different units.
My high school used that "objectives" system less and less as I moved up the grades -I assume that most teachers got tired of it pretty quickly and just decided to make their usual teaching material "look like objectives" rather than rebuild their curriculum in later years.
The implementation varied between classes - in my World History class, there were a large number of objectives, and each objective was met by a small quiz that tested ~one skill. (There were a lot of retaken quizzes in that class.) In Biology, there were about 10 objectives for the entire semester, so you could still pass while missing a few small skills, as long as those missing skills were spread out among different units.
My high school used that "objectives" system less and less as I moved up the grades -I assume that most teachers got tired of it pretty quickly and just decided to make their usual teaching material "look like objectives" rather than rebuild their curriculum in later years.