Our school district starts MAP tests for Reading and Math from 1st grade. They tested 3 times at beginning, middle and the end of school year to monitor the progress for individual student. It is an adaptive computer-based test. So every time your kid take it, the problem set would remember the previous stage and adjust to suit her needs. There is no time limit that I am aware of for the test. And I don't know if the process speed would affect the test score, but they do show a timer on screen. If your kid is at advanced level, be prepared. The problems could be wildly challenging beyond her capacity. I knew one 4th grade girl cried out loud when she was frustrated by an math problem on infinitely nested recursive radical sequence.
