Along the way through school and university I was very lucky to always have one or two fellow students who didn't mind explaining things to me. I would fight with some concept and then when I hit a wall, it would normally be fellow students who helped me climb it rather than the teachers. The idea of 'The Curse of Knowledge' is that once you understand something, it is very difficult to ununderstand it. Like watching the first season of a TV series with someone who is playing catchup. They ask a question and your answer is not the answer of someone who is also watching the series for the first time. Who is Jon Snow's mother? Why doesn't Jon Snow know?
There are various friends who really helped me. At the end of our last year of school, we used to write messages on a school shirt. One friend questioned who I would be able to call now that we were heading in different directions. This was pre-cell phones and the landline would be in the passage. A lot of my studying was done sitting on the phone. The real advantage those who are quicker out the gates have in explaining is that they still remember what it was like to not understand. When they answer a question, they are answering your question - not the one they think you should be asking.
Teaching someone else something also benefits the teacher. There was one particularly challenging subject at university, ironically called Survival Models (an improvement on the old name - Mortality), which most of my class failed. Repeating it again the next year, I learnt most of what I learnt by teaching fellow students. I couldn't claim to be an expert. Quite the opposite. I had just failed to get what I needed to get the previous year. What I had was a combination of an incentive to really understand the work, and an understanding of what it was like not to understand. I was a little bit further. I ended up doing very well second time round. In an ideal world, if you really want to understand something rather than just finish something, perhaps it is worth doing it twice.
My Dad went to a tiny high school in Swaziland where there were often people from multiple years in one class. I think this is a model that more schools and universities should adopt. Kids and students are probably in a much better position to teach each other. Salman Khan of the Khan Academy talks of 'switching the classroom' where you do homework at school, and schoolwork at home. Lessons can be recorded and an individual can work through them at their own pace. Pausing and replaying without the baggage of putting their handing up and effectively telling everyone they don't understand. The homework can then be done in the classroom, surrounded by other students who would be able to help. Having mixed classes and mixed age groups could do wonders here.