SchoolOO's PersonDAO makeover

GrupoDePessoas.cs

using System.Collections.Generic;
using System.Linq;

namespace SchoolOO.DAO
{
    public class GrupoDePessoas
    {
        public IList<Person> PorOrdemAlfabetica()
        {
            using (SchoolEntities schoolContext = new SchoolEntities())
            {
                return schoolContext.People.OrderBy(x => x.FirstName).ToList<Person>();
            }
        }

        public void Inserir(Person person)
        {
            using (SchoolEntities schoolContext = new SchoolEntities())
            {
                schoolContext.People.AddObject(person);
                schoolContext.SaveChanges();
            }
        }

        public void Atualizar(Person person)
        {
            using (SchoolEntities schoolContext = new SchoolEntities())
            {
                Person pessoaParaAlterar = schoolContext.People.Single(x => x.PersonID == person.PersonID);
                pessoaParaAlterar.LastName = person.LastName;
                pessoaParaAlterar.FirstName = person.FirstName;
                pessoaParaAlterar.HireDate = person.HireDate;
                pessoaParaAlterar.EnrollmentDate = person.EnrollmentDate;
                schoolContext.SaveChanges();
            }
        }

        public void Retirar(Person person)
        {
            using (SchoolEntities schoolContext = new SchoolEntities())
            {
                schoolContext.DeleteObject(person);
                schoolContext.SaveChanges();
            }
        }

        public void Retirar(int id)
        {
            using (SchoolEntities schoolContext = new SchoolEntities())
            {
                Person pessoaParaRetirar = schoolContext.People.First(x => x.PersonID == id);
                // Opcional: chamar método acima passando o objeto da linha anterior.
                schoolContext.DeleteObject(pessoaParaRetirar);
                schoolContext.SaveChanges();
            }
        }
    }
}