I maintain a database of questions. For each question, I assign it two metrics that describe its difficulty: "[Unnamed concept]" and "complexity".

"[Unnamed concept]" is how much you have to know about the topic; how much expertise is required to answer it competently. "Complexity" is how much "stuff" there is going on in the question.

Questions that are high in "[unnamed concept]" and low in "complexity" are elegant and deep. Questions that are low in "[unnamed concept]" and high in "complexity" are closer to "busywork". Maybe still challenging to get through everything without making a mistake, but not in an interesting way.

For example, in math, here's a question that's high in "[Unnamed concept]" and low in "complexity":

Two circles of the same radius overlap by a distance of that radius. What's the area of the overlapping section?

And here's a question that's low in "[unnamed concept]" and high in "complexity":

What is (2 + (4 / 5)) - (65 * ((3 / 5) + 20))?

When demonstrating a new concept, you want a question that's low in "complexity", since high "complexity" questions will distract/overwhelm the learner with irrelevant other things to think about.

High "complexity" questions are good repetative work for helping someone internalize/memorize a process and become good at executing it quickly and reliably.

In a not-quite-synonymous-but-kinda-close-in-many-cases definition, "[unnamed concept]" refers to the difficulty of figuring out the answer to the question, while "complexity" refers to the difficulty of figuring out what's being asked in the first place. (Excluding domain-specific knowledge, which falls under "[unnamed concept]".)

I want a name for "[unnamed concept]". The first word that comes to mind is "difficulty", but that's not accurate because my concept of "complexity" also contributes to a question's overall difficulty.

Ideally I'd like it to be a single word, or maybe two short words. (My use-case requires it to fit in a small amount of space, just like "complexity" can.)

Resolves NO if I haven't found a good name for this in a week.

If this doesn't seem like a coherent concept to you, or you think there's a better way to subdivide the different aspects of "difficulty", I'd be interested in that too.