This evaluation type checks if the coordinate in the Definition field is a solution to the equation in the student’s answer within a specified precision range. It is the numerical version of the evaluation type eval eq exact, which I suggest reading about first. In other words, if we substitute the coordinates in the definition field into the student’s answer, then the left-hand side and the right-hand side of the student’s answer cannot be more than Precision apart.

The coordinate in the Definition field should be formatted as a list, like [x=3,y=4]. If the student’s answer is not an equation, the system will give an error.

Examples:

This evaluation type also has boxes “Range low” and “Range high”, but these are ignored by the system.

It is not possible to check multiple coordinates in the same evaluation. For example, if you want to check in the negative feedback if both [x=3,y=4] and [x=5,y=6] are solutions to the student’s equation, then two separate feedback rules should be made.

Technically, what this evaluation type does is it checks if is(radcan(abs(subst( definition field , student’s answer )))<= precision) evaluates to true, where a student’s answer x+1=y would be replaced by x+1-y in the code. Documentation on the Maxima function subst can be found here.

This means that if we want to check multiple coordinates in the same feedback rule, we could also write an eval statement feedback rule with multiple subst functions in it instead of creating a separate feedback rule for every coordinate.

Example:

Do note that in this case, you need to check manually (either in the same eval statement rule or in any other feedback rule) that the student’s answer is in fact an equation. The example above does not do this.

❗ Note that this evaluation type does not have automated feedback.

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.