<mat-accordion *ngIf="subjects">
  <mat-expansion-panel hideToggle *ngFor="let subject of subjects">
    <mat-expansion-panel-header>
      <mat-panel-title>
        {{subject.name}}
      </mat-panel-title>
    </mat-expansion-panel-header>
    Grades:<br>
    <span *ngFor="let grade of subject.studentsAssoc![0].student.grades" [matTooltip]="grade.description">
      <span *ngIf="grade.subjectID === subject.id">{{grade.mark}},</span>
    </span>
  </mat-expansion-panel>
</mat-accordion>