The phrase "stakes attached" is an idiomatic expression that means there are consequences or repercussions involved in a particular situation. Full definition
Certainly there are those within the state who are working hard to eliminate the tests altogether and / or eliminate the high stakes attached for students. (gse.harvard.edu)
Rather than having regular check - ups on student progress, with relatively low stakes on those results, we'd have much higher stakes attached to a smaller number of test scores. (educationnext.org)
Others worry because teachers unions are calling for a moratorium on stakes attached to student testing until the new CCSS standards have been fully implemented, which may take several years. (educationnext.org)