The evaluation type “is not fraction” is hit when the student’s answer is not a fraction. Mixed fractions (like 1 ¼ which is equivalent to 5/4) are not recognized as fractions. This evaluation type has automated feedback, which is shown in the image below. The feedback rule in the image is in the negative feedback.
The evaluation type “is not rational” is hit when the student’s answer is not an integer or a (mixed) fraction. This evaluation type also has automated feedback, which is shown in the image below. The feedback rule in the image is in the negative 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.