The evaluation type eval normal checks if the student’s answer is mathematically equivalent to the expression in the Definition field.
Some examples of eval normal used in negative feedback are given below, but we can also use this evaluation type in positive feedback or the solution definition.
More technically, the expression in the Definition field and the student’s answer are both converted to their canonical normal form and then compared to each other. The conversion to the canonical form is done using the Maxima function radcan. Documentation about this function can be found here. In essence, it is checked if is(radcan(student’s answer)-radcan(definition field)=0) evaluates to true.
The evaluation type eval normal is quite similar to the evaluation type eval exact. The difference is that in eval exact, less simplifications are done to the student’s answer before comparing it to the expression in the Definition field.
Note that this evaluation type does not have automated feedback.
More on evaluation types
An overview of all evaluation types can be found here (for mathematical answers) and here (for text-based answers). More detail on the different fields of a feedback rule can be found here.