If students have the opportunity to keep trying until they meet a standard how can we differentiate between the ones who meet the standard right away and the ones who take multiple attempts?

Answer:

We do not, nor have we ever differentiated between students who meet standards quickly and ones who take more time.  Young adolescents simply do not develop at the same rate.  Nowhere in the K-12 landscape do we work with students with such wide ranges of development in all domains: cognitive, social, emotional, physical, the ability to think abstractly, etc... Adolescents simply do not develop at the same rate and they certainly do not learn at the same rate or in the same way.  When students have demonstrated they have met a standard or learning target, we report that they have done so based on the evidence (work samples) teachers have collected.  The criteria for meeting a standard remains the same regardless of how a student gets there or how long it takes them.  The following quote from Thomas Guskey helps to illustrate the concept:

“Is my purpose to select talent or develop it?…If your purpose as an educator is to select talent, then you must work to maximize the differences among students. In other words, on any measure of learning, you must try to achieve the greatest possible variation in students' scores …Unfortunately for students, the best means of maximizing differences in learning is poor teaching. Nothing does it better.  

If, on the other hand, your purpose as an educator is to develop talent, then you…clarify what you want students to learn and be able to do. Then you do everything possible to ensure that all students learn those things well. If you succeed, there should be little or no variation in measures of student learning. All students are likely to attain high scores on measures of achievement, and all might receive high grades".

-- Thomas R. Guskey, Education Leadership,
    ASCD, November 2011, Pages 16-21


When you look at the research on predictors of success we, find that perseverance, sometimes referred to as "grit" is a far better predictor of success than innate ability or even academic success.  It's growth mindset, tenacity and perseverance that have been shown to be the best predictors of success regardless of the field.  It is true in academia, the corporate world, sports, the military and so on.

This idea is further illustrated in this TED Talk by Angela Lee Duckwork:

The Key to Success? Grit.