with_obj_modern.cs

using System.Collections.Generic;

namespace journey_01.final
{
    public class Person
    {
        public int ID { get; set; }
        public string Name { get; set; }
        public List<string> Classes { get; set; } = new List<string>();

        public bool IsInClass(string cls)
        {
            return Classes.Contains(cls);
        }
    }

    public class Teacher : Person
    {
        public short Parking { get; set; }
    }

    public class Student : Person
    {
        public float GPA { get; set; }
    }

}