I feel you more than ever. We started identifying this long-term debt as `non-linear learning gaps'. As other folks have called out, large chunk of students in higher grades or higher ed need to understand the most basic of stuff referring back to multiple years of grades in their past. The good part is you can do that in a human conversation, go back or ahead of your current grade-level seamlessly in a conversation as your mind creates a mental-model of what you are learning. The 'going-ahead' part is specially important as it build perspective into 'why' of learning a concept.

In short, we believe the long-term debt is fixable.