To students like me, teachers are mythical creatures. Sure, I see them every day, but I can’t see behind the proverbial curtain. I don’t know how they judge their success or failure in different areas, how well they are serving their students as a whole, or how they communicate information about their teaching performance to their peers. In the absence of good evaluation systems, that same ambiguity extends to parents and administrators.

As Ben Orlin recently pointed out in the Atlantic, teachers are only human. Some great teachers may portray their performance as mediocre or poor, and some less effective teachers may be inclined to exaggerate their success. In either case, it’s clear that some kind of evaluation system is necessary if we want our teachers to be fairly and accurately assessed.

Here in Colorado, SB 10-191 ostensibly aims to provide such a system. Among numerous other things, the law requires all Colorado school districts to adopt new yearly performance ratings. These ratings have been in the “practice” phase for the past few years, but are due to be fully implemented in the coming school year. That means that teachers who receive ratings below “effective” for two consecutive years will lose their tenure. In contrast, teachers who earn “effective” ratings or better for three consecutive years will be awarded tenure.

SB-191 has not come without issues. The Colorado Department of Education provides a model evaluation system that districts can adopt, and many have. However, other districts—particularly those in rural areas—remain skeptical. As I outlined in June, Holyoke School District is seeking a waiver for some of the law’s provisions under a 2008 innovation law. Kit Carson, another rural district, received a similar waiver for some of SB-191’s requirements in 2011 amid a fair amount of legal confusion. It remains to be seen if other districts will follow suit.

Meanwhile, some of Colorado’s largest teachers unions are continuing their push against other SB-191 provisions involving teacher placement despite a Denver judge throwing out their original suit earlier this year.

Clearly, questions remain about what constitutes a good, fair, and feasible evaluation system. How can districts ensure that their evaluation criteria are tied to the outcomes they value most? How heavily should student test performance be weighted in an evaluation system that incorporates multiple measures? How can districts best incentivize and reward good performance? Perhaps most importantly, to what extent should such a system be standardized across districts operating in different contexts?

These are complex questions, and they will take time to answer. Even so, they must be considered as the 2014-2015 school year approaches and SB-191 moves closer to full, teeth-and-all implementation.

In the meantime, I have a few more weeks of summer to enjoy before the school bell rings again.