The main problem with our educational system

When nearly everything in education is dependent on the quality of the teachers, then if you want to improve the quality of education, you have to have, and retain, the best teachers.

The Best Teachers in the World | Hoover Institution:

Unfortunately, due to a confluence of circumstance this is impossible in the US. The first of those circumstances is the hodge-podge approach to local, city, county, state and federal, each operating essentially independently, funding for education we spend far more on administrative tasks than on teacher salary. But teacher salary won't solve the problem. Teachers unions make it increasingly difficult to get rid of the bad teachers and there is no way to get any reliable method of teacher evaluation through the roadblocks thrown up by teachers unions. The system of training and certification of teachers is also deeply flawed. There are other serious problems as well, but those spring to mind as pretty big obstacles.

The secrets of sleep

...by which we mean that sleep is full of secrets that we have no idea about. It's kind of silly when you think about it: it's one of the most central activities of our lives. We spend easily a third of our lives doing it, and yet we know virtually nothing about it, the mechanisms behind it or even why we need it.

Oh, sure, we know some of the chemicals involved, we know the effects, but the deeper questions of why and how precisely our body accomplishes the task are still quite beyond our understanding.