What are these "masteries" really showing us?
Honestly?
I've looked at this as DD has attempted to use Khan as a supplemental instructional tool.
IMO, most of the "mastery" doesn't necessarily represent actual "mastery" the way that I think about it because of the way that assessments are structured and offered via Khan.
So that's strike one, IMO, in terms of using the software itself to evaluate what a student truly has mastery over...
secondly, recognize that the way that math is taught now, there is spiraling. I'd expect that a 2nd grader with complete mastery of 2nd grade WILL have mastered about 10% of what is on offer through 6th grade-- meaning, in each year's topics-- because of that spiraling.
I noticed this in jumping around and playing with it to see how good the software was; I could "relearn" things that I probably never really "learned" the way Khan apparently "teaches" them-- trig topics, for example, or those in stats that use different notation-- in a VERY short amount of time simply through trial and error on those assessments. That is so not to say that I have "mastery" over those topics, however. I couldn't tell you HOW to use the equation of a parabola to determine what its graph should look like to save my life-- truly-- but that topic shows that I've "mastered" it, because I was able to "pass" five questions in a row through raw trial and error discovery.
Now, I don't know whether that is entirely relevant here, since I'm an adult, and my LOG is similar to most of the kids around here, plus I've obviously had all of those topics previously-- it's just been 35+ years or so in that particular case...
but still, it makes me think that being able to USE the concepts isn't what Khan is actually measuring, even if they think that they are. KWIM?
I wouldn't really worry too much about this at the K-6 level, though. Not with an HG+ kiddo-- they'll learn to fill in whatever gaps they have in a hurry, IMO, up until high school level at least.
