Nested eager loading with constraint not working

I am having hard time using nested with with constraint. Can someone help me to group subjects based on the what semester it will be offered.

MyController

    public function show($id)
    {
        $student = Student::with(['course', 'course.curriculum', 'course.curriculum.subjects' => function($query){
            $query->groupBy('sem_offered');
        }])->findOrFail($id);

        return view('students.show', compact('student'));
    }

show.index

@foreach($student->course->curriculum->subjects['first first-sem'] as $subject)
<tr>
    <td></td>
    <td></td>
    <td></td>
    <td></td>
    <td>98</td>
</tr>
@endforeach

via Chebli Mohamed