I've learned that certain things are much harder than when you write about them in a book.

I realized that there are many people who are very good students, but they think of themselves as bad students. At the end of the day, what they are really missing is way to understand where their gaps are and a way to address those gaps.

I grew up with plenty of smart people. They would beat me at chess; they could solve brain teasers before I could, but then they would struggle in algebra. These were incredibly smart people who simply did not have the foundation in math that I had.

Sal Khan Quotes