Our partiular problem locally is the practice of "social promotion." Elementary and middle school students are passed on to the next grade regardless of whether they actually earned a passing grade, under the assumption that keeping them with other students their age will push them to work harder to reach the same level as their friends.
It doesn't work, and no policies have been implemented to change it, so our high schools are virtually full of teenagers with 4th grade reading levels. *sigh*