I made this presentation to support the listening exercise on p. 34 of JHS New Horizon 3 (2020) that discusses food miles.
The text essentially says more miles are bad, less miles are good. But that's too simplistic. At the risk of becoming too complicated, I wanted to show that it's a complex situation with no clear answer (see https://www.independent.co.uk/climate-change/news/food-miles-does-distance-matter-5329199.html)
I use an example of pineapples grown in the UK vs Ghana, with the intention of being consumed in the UK. Because UK pineapples need to be grown in hothouses, they use significantly more CO2 than those grown (organically) in Ghana (by the company Blue Skies, see https://global.blueskies.com/blueprint/).
Even with air transport, the emissions from Ghana pineapples is less than that of UK pineapples. This is largely because most air freight is shipped on passenger planes that would be flying anyway, even without the additional cargo. (The vast majority of food is actually transported by sea, which is much less emissions intensive, but I don't get into this in the lesson. See https://ourworldindata.org/food-transport-by-mode.)
Finally, importing pineapples from Ghana supports farmers and their families. As Ghana is a developing country, this kind of income is essential for many of their citizens to escape poverty, improve infrastructure, etc.
As for the lesson structure, we went through p.34 steps 1-3 and then did this presentation. I felt like it made the students think differently about the topic. It's important to note that this is just one example, and other imported foods may indeed have a greater environmental impact, depending on many factors. If anything, I hope it encourages students to be critical of what they're told, to question authority, and become more curious. If you use this, let me know how it went, or how it could be improved. Thanks!