How would you teach the form ‘(be) going to + infinitive’ used for future plans to a pre-intermediate class?

Outline your lesson plan using the following headings as a guideline.
Warmer / Lead in
Presentation (in a suitable context) and drilling
Controlled practice activity
Production (a personalised communicative activity)
Briefly say what you would do for each stage of the lesson (in bullet point). Each of the four stages above may contain more than one activity.
Remember to include examples of the sentences you will present and your students will practise. The sentences should follow this pattern: Subject + ‘am/ is /are going to + verb’ and they should express future plans.
Also include concept questions you would use to check understanding.
(Min 200 words).