At key stage 2 pupils should be taught about "how places are interdependent" (PoS 3g) "for example, movements of people". There is a very good treatment of this subject for primary aged pupils on the Global Eye website www.globaleye.org.uk At KS3, "population distribution and change" is a key theme of the PoS (6f), as is the requirement to study "places and environments in the news" (PoS 3a). This theme is also part of GCSE and A-level syllabuses. A good activity would be a geographical enquiry through where, what, why, how and when questions.
The topic could be linked with citizenship at KS3 "1i - the world as a global community" and 4 and "1j - the wider issues and challenges of global interdependence".