Any tips for this challenge - Updating Entities - appreciated.

using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;

namespace Treehouse.CodeChallenges
{
    public static class Repository
    {
        public static List<Course> GetCourses()
        {
            using (var context = new Context())
            {
                return context.Courses
                              .OrderBy(c => c.Teacher.LastName)
                              .ThenBy(c => c.Teacher.FirstName)
                              .ToList();
            }
        }

        public static List<Course> GetCoursesByTeacher(string lastName)
        {
            using (var context = new Context())
            {
                return context.Courses
                              .Where(c => c.Teacher.LastName == lastName)
                              .ToList();
            }
        }

        public static Course GetCourse(int id)
        {
            using (var context = new Context())
            {
                return context.Courses
                              .Include(c => c.Teacher)
                              .SingleOrDefault(c => c.Id == id);
            }
        }

        public static void AddCourse(Course course)
        {
            using (var context = new Context())
            {
                context.Courses.Add(course);
                context.SaveChanges();
            }
        }

        public static void UpdateCourse(Course course)
        {
            using (Context context = GetContext())
            {

                RepositoryToUpdate.SeriesId = repository.SeriesId;
                Repository.Entry(repositoryToUpdate).CurrentValues(repository);
                context.Repository.Attach(repository);
                context.Entry(repository).State = EntityState.Modified;
            }
        }
    }
}