The use of the past participle

Mrs. D., an exhausted French teacher, is struggling to manage her daily life: some students are lagging behind, the school program is pushing her to move faster, and there are even those who judge her work harshly. But Mrs. D. doesn’t want to deviate from her mission for anything in the world. Caught between dream and reality, she will not rest until all her students, without exception, have understood the rule of past participle agreement.