A storm in a tea-cup?

Why has a box of tea increased by 30% since this time last year? This article is excellent for applying demand /supply diagrams to the market for tea. For Year 10s at this time of year, I pair the pupils up, give them the article and ask them to create exam style questions based on it, then they swap their questions with another pair whose job it is to write the answers. The original pair then mark the work.