Column not found: Unknown column in where clause

Need Help
1

Following is the association

$this->table('school');

$this->belongsTo('Districts', [
    'foreignKey' => 'district_id'
]);
$this->hasMany('Students', [
    'foreignKey' => 'school_id'
]);

Each school has many students
Each school belongs to a district

Let’s say there are 4 districts. (Districts.id = 1,2,3,4)
In School’s Model, I’m trying to fetch the list of all students.
But if the district is 1 or 2, I want to show only those students who scored more than 50 marks.
And for the other districts, I am trying to show students who scored less than 35 marks.
This is the finder function I wrote for the above mentioned.

public function findStudentsList(Query $query, array $options)
{ 
    $query->select(['id','name','modified','created'])
    ->contain([
        'Districts'=> function ($query) {
            return $query->select(['id','name']);
        },
        'Students'  => function ($query) {
            return $query->where([
                'CASE 
                WHEN Districts.id=1 THEN Students.marks >50 
                WHEN Districts.id=2 THEN Students.marks >50 
                ELSE Students.marks < 35 
                END']);
        }		
    ]);
}

But when I execute this, I get the following error.

Column not found: Unknown column 'Districts.id' in 'where clause'

Is this the right way to do it? I’m new to CakePHP3.

2

Used district_id instead of Districts.id and it worked.