declare @pJSON varchar(max) = '
{
    "School": "MiddleSchool",
    "Password": "SchoolPassword",
    "Attributes": [
        {
            "Type": "Exam",
            "Value": "1"
        },
        {
            "Type": "Class",
            "Value": "11b"
        },
        {
            "Type": "Math",
            "Value": [
               {
                    "ExamDate": "2019-01-01",
                    "Points": 100,
                    "Grade": 10,
                    "Notes": "Good"
                }
            ]
        }
    ]
}   '


select ExamDate, Points, Grade, Notes
from OPENJSON(@pJSON, N'$.Attributes[2].Value')
cross apply openjson ([Value])
with
(
  ExamDate date,
  Points int,
  Grade int,
  Notes varchar(max)
) as [value]

select ExamDate, Points, Grade, Notes
from OPENJSON(JSON_QUERY(@pJSON, N'$.Attributes'))
with
(
  ExamDate date      N'$.Value[0].ExamDate',
  Points int         N'$.Value[0].Points',
  Grade int          N'$.Value[0].Grade',
  Notes varchar(max) N'$.Value[0].Notes'
) as [value]
WHERE ExamDate IS NOT NULL;