I know they don't really matter when it comes to grades, but I have seen just how much these test scores matter in terms of placement. One MAPS test in 2nd grade determined which math level my daughters would be placed in for all of 3rd grade. They said kids would be moved accordingly during the year. Never saw it happen.
Our school is in the process of determining which students will be admitted to GATE next year. There are a few steps in the process but only students that score at a certain level the state tests the year BEFORE even get to continue being evaluated. So again a single test taken in 2nd grade will affect their placement in 4th. If the OP's school works in the same way, I think the she would be wise to work on this with her child. It really could matter down the line. ...