C4.26. Element pl-sketch: Advanced grading examples

To grade curves drawn with pl-sketch tools like free-draw, spline or polyline, it is often easiest to compare them to a reference function via the match-function grading criterion. This criterion can also be used for partial or piecewise functions when the comparison is delimited by an x-range parameter.

For full marks, draw the function $$ f(x) = \begin{cases} x & \text{if } x < 0 \\ x^2 & \text{if } x \geq 0 \end{cases}. $$

When splitting up grading criteria as in the example above, giving partial points per criterion is often desirable. To prevent giving any partial marks unless the full function is correct, it is possible to use stage parameters and a dummy criterion that assigns points when all other grading criteria are satisfied.

For full marks, draw the function $$ f(x) = \begin{cases} x & \text{if } x < 0 \\ x^2 & \text{if } x \geq 0 \end{cases}. $$

The xy-flip parameter allows the grading of curves that represent functions of $y$. Because this parameter also changes the interpretation of some grading criteria, we recommend testing question with this parameter carefully to make sure they match the expected grading logic.

For full marks, draw the curve $x = y^2$.