Although I don't like the idea of any kind of universal theory or method working for all people at all times I think these are four good steps for how to integrate in a way that is authentic and useful and helps to break down the barriers that education erects between different disciplines or subjects.
1) Develop a real world question with students
2) Make sure everyone, teachers and students, understand how the core subjects can contribute to a sophisticated exploration of this question
3) In class learn the skills and knowledge that each subject can offer in regards to the main question
4) Provide an opportunity for students to use this new learning to explore the question in new and creative ways.
