I think with Khan Academy, if a kid answers about 2 questions correctly on a topic, it considers them "mastered". I would take it with a grain of salt. DD has done it a few times and took the placement test, and then started doing the lessons in the order that it gave her. It was jumping around all over the place. One question would be "find the perimeter of this square" and then the next question would be something from high school alegebra. Since the placement test she took had a total of about 20 questions, I don't think it is a good instrument to use to find out what level they are at or what they should be working on. ALEKS is probably better in terms of having an "assessment" but you have to pay for it and I don't think it has any instructional videos like Khan Academy does (someone correct me if I'm wrong). With Khan Academy, I told DD that the next time she does it she should go into the fourth grade level and do things in order (skipping things she already knows), rather than skipping around all over the place from one grade level to the next randomly or doing it in the order that they throw things at her.
Programs like this have a lot of limitations but the fact of the matter is that when it comes down to it, I have a choice between trying to teach DD these concepts myself, or allowing Mr. Khan to do it for me. Her teacher isn't teaching math above a third grade level and she already has the third grade math curriculum mastered. He is much better than I am. If she gets stuck then I am there to try to help, but with the higher level math I am pretty useless and have to scream for Dh to come help (he majored in math).
We have a subscription to IXL but I have never seen a placement test on it. It does give info about what skills the child is proficient in as they do the lessons but that's pretty much it, as far as I know. So if a child masters 2 digit multiplication with regrouping, as an example, and they finish the lesson or get enough correct, it will consider that skill mastered. I think this is what they mean by the program assessing or monitoring progress.
