LANSING, Mich. (AP) — An initiative to improve Michigan third-graders’ reading is caught up in a dispute among lawmakers about making students repeat a grade if they lag too far behind.

The clash is big enough that the early literacy bill was sent to a House-Senate conference committee to resolve differences.

Third grade is considered a key benchmark because it is the last year students learn to read before transitioning to reading to learn. Sixteen states require the retention of third-graders who do not meet grade-level expectations in reading.

Key sticking points in Michigan include the level of parental involvement in deciding whether a child should be held back and the number of exemptions under which kids could still advance to fourth grade for “good cause.”