Based on some of the queries received in the CRAI Teaching Unit, we propose an example grading system in case it could be useful as a reference.

It is a grading system with all its elements graded out of 10 (except for class attendance, which is graded out of 1) and with two main categories:

Continuous assessment and Single assessment, the overall course category is set up with the aggregation method "Highest grading" so that the system takes the higher of the two assessments in case a student, for some reason, has done both assessments.
 

The single assessment category consists of only one grading element without any extra settings with the aggregation of "average of the grades".
 

The continuous assessment category consists of a subcategory called "Continuous weighted elements" where we will put all the rest of the elements of the continuous assessment category except one element called "Attendance" the aim of this category is to be able to add the element "attendance" as extra credit, not being added to the grade if it has reached its maximum grading, and where we will be able to add extra grading to the total if the student has attended class regularly (maximum 1 point out of 10).
 

Within the category "continuous weighted elements" we will define two subcategories, the first one with some elements of "Voluntary performance" with a weight of 10% of the mark, and another one of "Compulsory performance" with the remaining 90% of the mark.

In turn, this last subcategory of compulsory performance is subdivided into two further subcategories, namely "compulsory tasks" (two), which account for 60% of the mark, and a compulsory quiz, which accounts for the remaining 40% of this subcategory.

In the case of the subcategory "Compulsory tasks" we will configure the aggregation method as "average of the grading" as we want both tasks to be averaged.

Outside this subcategory and within the category "Compulsory tasks" we will place the questionnaire "quiz continuous assessment" so that we can select as aggregation method "Compulsory tasks" weighted average of the grading assigning a weight of 60% of the grade to the tasks and 40% to the quiz.

Within the category "Continuous assessment" we will place the element "Attendance" which, as we mentioned at the beginning, is an extra point. In this category we will select "Natural (Sum of grading)" as the aggregation method, otherwise it would not allow us to configure the element "attendance" as an extra credit.
 

The category "Continuous weighted elements" will have a weight of 100% of the mark and the extra credit 0%, as the system, knowing that it is an extra credit, will only add the mark if the maximum mark has not been reached.

With this configuration, we would already have our grading system ready with the two options of Continuous Assessment and Single Assessment.

We can go one step further and set conditionals:

Let's suppose that for the final mark to be calculated we want that at least the mark of the category "voluntary completion" and that of "compulsory completion" are higher or equal to 4'5 in affirmative case the sum of the category "continuous weighted elements" and the element "attendance" will be done otherwise a 0 will be put.

To do this we do Edit calculation to the total of the category "Continuous Assessment".
 

The first thing to do is to add ID numbers to the categories involved in the calculation, add the names to the blanks (without brackets) and click the "add ID number" button at the bottom of the page.

It should look something like the image below:

Now we add the operation to the calculation box:

And save the changes.

More help on grading calculations can be found at this link:

https://docs.moodle.org/311/en/Grade_calculations

Note: Once the calculation has been saved, if you edit the parameters of the "Continuous assessment" category, you will see that the "aggregation method" section has disappeared, as it has been replaced by the calculation.