如何生成嵌套的IENumerable？

public class Student
{
    public string Name { get; set; }
    public int Age { get; set; }
}

public class Class
{
    public string ClassName { get; set; }
    public IEnumerable<Student> Students { get; set; }
}

List<Student> students1 = new List<Student>()
{
    new Student() { Name = "张三", Age = 18 },
    new Student() { Name = "李四", Age = 19 }
};

List<Student> students2 = new List<Student>()
{
    new Student() { Name = "王五", Age = 20 },
    new Student() { Name = "赵六", Age = 21 }
};

List<Class> classes = new List<Class>()
{
    new Class() { ClassName = "一年级", Students = students1 },
    new Class() { ClassName = "二年级", Students = students2 }
};

foreach (var classObj in classes)
{
    Console.WriteLine("班级名称：" + classObj.ClassName);
    Console.WriteLine("学生信息：");
    foreach (var student in classObj.Students)
    {
        Console.WriteLine("姓名：" + student.Name + "，年龄：" + student.Age);
    }
    Console.WriteLine();
}