Concept Exercises aim to teach a student the key skills needed to work in a given language. They cover both how to do common things in that language (e.g. how to manipulate strings) and how to do more language-specific things (e.g. monads, OOP, higher-order functions).
Concept Exercises have the following characteristics:
Exercises are unlocked based on concepts taught and learned. Each Concept Exercise must teach one or more concepts. It may also have prerequisites on Concepts, which means it will not be unlocked until Concept Exercises teaching those prerequisite concepts have been completed.
Concept Exercises should not become inherently more difficult as the track progresses. A seasoned developer in Language X should be able to work through all the Concept Exercises on that track spending no more than 5-10 minutes solving each one. As each exercise should be focused on getting someone to use a concept for the first time, and because the seasoned developer already understands that concept in Language X, the exercise should feel relatively trivial for them. Later exercises may feel more difficult to a developer unfamiliar with Language X, but only because the later exercise is teaching a concept which in itself is more complicated (for example, most people would agree Recursion is a more complex topic to learn for the first time, than a Loop is to remap from one language to another).
Concept Exercises are not mentored. When a student submits a submission that gets the tests passing for a Concept Exercise, we check for an Analyzer or Representer to give feedback. If none is found, then the solution is approved. This shifts the burden of teaching to the exercise, which must provide a clear pathway to learning the concept that is being taught.