using System;

using System.Linq;

​

​

class School

{

    public Student[] Students{get;set;}

    public String SName{get;set;}

}

​

class Student 

{

    public string Name {get;set;}

}

​

public class Program

{

    public static void Main()

    {

        var schools = new [] {

            new School(){SName = "School1",  Students = new [] { new Student(){ Name="Bob"}, new Student(){ Name="Jack"} }},

            new School(){SName = "School2",  Students = new [] { new Student(){ Name="Jim"}, new Student(){ Name="John"} }}

        };

        var allStudents = schools.SelectMany(s=> s.Students);

        var directory = schools.SelectMany(p => p.Students, (parent, child) => new { parent.SName, child.Name });

        foreach(var student in directory){

            Console.WriteLine(student.SName + "  " + student.Name);

        }

    }

}