"De leraar beoordeelt de verhalen die de leerlingen hebben geschreven."
Translation:The teacher judges the stories that the students have written.
And I wrote: "The teacher assesses the stories that the students wrote." Duo marked this incorrect and let me know the correct answer was: "The teacher assess the stories that the students wrote." Duo seems to have a subject-verb agreement problem here: it must indeed be "assesses" in this case.