Two companies offer licensing options for schools.  It is important to review the conditions for licensing.  For example, normal licensing does not include showing a movie outdoors. 

Keep in mind that each company can only license movies for which it has obtained permission to do so.  If you are interested in a specific movie, make sure the company includes that movie in its catalog.

• Performance of or Showing Films in the Classroom 
  This article from the American Library Association clarifies the use of digital content in the physical classroom.
• Movie Licensing USA 
  Movie Licensing USA is the exclusive provider of one-time and annual Public Performance Site Licenses to K-12 Schools and Public Libraries for the following studios. Licenses content from major Hollywood Studios including Walt Disney Pictures, Paramount Pictures, Warner Bros., Sony Pictures, NBC/Universal Pictures, DreamWorks Pictures, New Line Cinema, Lionsgate Films, MGM, Touchstone Pictures, Hollywood Pictures, Columbia Pictures, TriStar Pictures, Focus Features, Miramax Films, Warner Independent Pictures, Paramount Classics, Paramount Vantage, Fine Line Features, United Artists, Picturehouse and Vivendi Entertainment.
• Motion Picture Licensing Corporation 
  Includes 20th Century Fox and over 390 educational and documentary producers including Scholastic Entertainment, History Channel, and Discovery Channel video.
• PTO Family Movie Night 
  Includes a free movie night planning kit and tips for hosting a successful movie night for schools.