Zad1
db.students_records.insertMany([
{student: {id:161969, name:"Jakub", surname:"Kotowski"},
 courses: [{id:1, name:"AKO", year:2, semester:3,
           grades: {lecture:3, laboratory:3, project:3, exercises:3, exam:3},
           lecturer: {name:"Jacek", surname:"Placek", title: "Dr"}},
           {id:2, name:"NBD", year:4, semester:7,
           grades: {lecture:4, laboratory:5, project:4, exercises:4, exam:4},
           lecturer: {name:"Gacek", surname:"Stasiek", title: "Inz"}}]
       },
{student: {id:160472, name:"Jan", surname:"Fan"},
 courses: [{id:3, name:"PP", year:1, semester:1,
           grades: {lecture:2, laboratory:2, project:2, exercises:2, exam:2},
           lecturer: {name:"Ziom", surname:"Bom", title: "Dr"}},
           {id:2, name:"NBD", year:4, semester:7,
           grades: {lecture:5, laboratory:5, project:5, exercises:5, exam:5},
           lecturer: {name:"Gacek", surname:"Stasiek", title: "Inz"}}]
           }])

Zad2
Aby dowiedziec sie na jakim semestrze jest student, moim odnosnikiem beda oceny, ktore odnosza sie do kursow, ktore sa prowadzone na najwyzszym semenstrze dla konkretnego studenta.
Zakladam, ze kiedy student przechodzi na nastepny semestr, to jest dla niego wstawiony wpis z pustymi ocenami (tak jak na MojaPG).

db.students_records.aggregate(
  [
    {
      $project: {
        "_id": 0,
        "student.id": 1,
        "student.name": 1,
        "student.surname": 1,
        "courses.year": 1,
        "courses.semester": 1
      }
    },
    {
      $unwind: {
          path: "$courses"
      }
    },
    {
      $group: {
        "_id": "$student.id",
        "year": { $max: "$courses.year" },
        "semester": { $max: "$courses.semester" },
        "name": { $last: "$student.name" },
        "surname": { $last: "$student.surname"}
      }
    }
  ]
)