title: How do I remove a single HABTM associated item without deleting the item itself?
body: <p>How do you remove a HABTM associated item without deleting the item itself?</p>
  
  <p>For example, say I have 3 Students that are in a Science class together.  How do I remove the Science objects from the StudentsClasses table without deleting the actual Science reference?  I'm guessing that    <code>Student.Classes.first.delete</code> isn't a good idea.</p>
  
  <p>I'm using JavaScript with drag-and-drop for adding and removing, not check boxes.  Any thoughts?</p>