The topic was solving systems of linear equations and while she thinks she understands the process of doing matrix arithmetic, Chandler is confused about other factors.
It’s difficult to describe how or why math works. It’s easier to just write the formula and say, “Do this.” Several readers have commented on this blog that what’s often missing from math education is more of a focus on why certain applications work. I agree. It’s harder to remember what to do, if you don’t have some sense of why it works.
Knowing why the formula works would be excellent, although Chandler is probably in the minority among high school Algebra II students in wanting to move beyond the basic mechanics of getting the task done.
However, even more important would be if she and the rest of her class were learning how people actually use this process to solve real problems.