In biblical Hebrew, the root קדש (kadosh) has two different meanings. It is used to signify sanctification, like in the word Kedoshim in verse 2, which gave this portion its name; and it also means distinguished or exclusive. The classic example for the second meaning is the word Me’kudeshet used in the Jewish wedding ceremony (otherwise known as Kidushin) to emphasize the couple’s commitment to establishing a life-long, intimate and exclusive relationship. This ambiguity creates yet another obstacle in the fulfilment of this mitzvah, but instead of clarifying, Moshe adds an even more confusing reason for this demand - “for I, the Lord your God, am holy.” Just like the first part of the verse, this is also not explained to the Israelites, or to us.
Many Rabbis and scholars tried to solve this mystery, and most of them agree that the commandments that follow this cryptic demand serve as the ‘manual’ for being holy. Some of these commandments seem like a perfect fit for this purpose: Honoring one’s parents (verse 3), refraining from idolatry (4) theft or deceit (11), leaving a portion of all crops for the hungry (9), and above all - “Love your fellow as yourself” (18), to name but a few. Other commandments mentioned here do not seem, at first, as essential or necessarily connected to holiness - however we choose to interpret it: keeping cattle from mating with a different kind, or from wearing clothes made from a mixture of two kinds of material (19), for example. Nonetheless, none of these commandments are explicitly described as even remotely connected to holiness.
And so, we are left with the ridiculous task of being holy, for which our tradition provides nothing more than a general guideline. But this conundrum could be turned around to offer a very liberating and empowering idea: It is the deeds that sanctify the person doing them, and not the other way around (and we are not going to tell you which deeds, either). This statement is important for people of all ages and for all realms of life. We are promised the world, perhaps even more, for keeping our tradition and being mensches. There is no fine print or other demand we must fulfil, but we have to find our own way. This message is as relevant for students as it is for teachers, parents and rabbis. At the end of the day, our ‘grade’ will be a product of the work we did in this world. And just like every mistake hurts the grade, there is always a chance to improve it, and even get an A+.