12.5. Setting up your grading formula

Once you have set up one or more categories (other than the built-in Uncategorised category) and entered some grades, you can set up a formula to compute the numerical course grade.

Keep in mind that this formula will be applied all through the semester, not just at the end. Students will be able to see their numerical course grade all along. To make sure that items not yet graded are not averaged into the course grade (as zeroes!), be careful not to move graded items from the Uncategorised category to their final category until you are ready to release the grades. See Section 11.2, “Grading an assignment” and Section 12.4, “Adding a gradebook column for an external grade” for the relevant procedures for assigning categories to graded items.

Procedure 14. Setting up a grading formula

From your course page, under Administration on the left, click the Grades link.
From the Choose an action... pull-down menu, under Categories and items, select Full view.
The last row of this table is labeled Course total. In the Actions column on the right-hand side, click on the Edit calculation icon.
Here is a small example. Category homework contains two homeworks named hw1 and hw2. There is one item named midterm in category exams.
You will need to define a symbolic name, called an id number, for each category so that you can use that category's average in your calculation. In the field labeled Category total for each category, enter a short name, which can be the same as the category name, and then click Add id numbers.
In the Calculation field, enter an expression that computes the course average as a function of the various categories and items. Then click Save changes.

The formula must start with “=” followed by a normal mathematical expression using these elements:

A reference to a category or item, in “[[...]]” square brackets. In the example, the value of hw1 is expressed as “[[hw1]]”.
The usual mathematical operators and parentheses: + - * / ( )
Assorted functions; see the table below.

To continue the example, here is the formula to compute the course grade as 70% homeworks and 30% exams:

=[[homework]]*0.7 + [[exams]]*0.3

In our example, we will assign id number homework to the homework category and exams to the exams category. Here is how the Edit calculation screen looks after we enter the id numbers and then type in the formula:

Here are the functions you can use in building your formula.

average(x, y, ...): Takes any number of arguments and returns their average.
max(x, y, ...): Returns the maximum value of its arguments.
min(x, y, ...): Returns the minimum value of its arguments.
mod(x, y): Returns the remainder when x is divided by y.
pi(): Returns the value of π.
power(x, y): Returns x to the y power.
round(x, n): Returns x with the fraction rounded to the nearest value with n digits after the decimal point.
sum(x, y, ...): Returns the sum of its arguments.
abs, acos, acosh, arccos, arccosh, arcsin, arcsinh, arctan, arctanh, asin, asinh, atan, atanh, cos, cosh, exp, ln, log, sin, sinh, sqrt, tan, tanh: Each of these mathematical functions takes one argument. Isn't it comforting to know that you can use hyperbolic trig functions to compute your course grade?

NMT Moodle 1.9 Instructor's Guide

12.5. Setting up your grading formula