Assignments (or jobs) are incompletely displayed constructions, which the user is supposed to finish. The computer will check for a correctly constructed target object. The construction itself might be different though. You find an example here. The user will receive a message, as soon as he has completed the construction.
Assignments are generated by choosing the last object, which should be displayed to the user. Furthermore, there must be target objects. The target objects will be displayed in a light color, unless they are hidden before the construction is saved.
Targets are not checked for the solution, if they are generated while pressing the shift key.
To test the assignment, click on the menu entry for this. In contrast to the web page, you will have the complete set of tools available, however.
Area objects as targets should be defined by the least set of corner points. If the solving user creates additional points on the sides of the polygons those points will be skipped.