Leo this is a great lesson, and I really appreciate that you shared it with everyone.
I teach a 2hr class once a week for korean english teachers and I used this lesson last week, albeit heavily modified. What I did was print about 6 of the photos from the website that featured them and then printed out reading material from Simple English Wikipedia to provide background and contextual information for each of the photos.
In class i put each picture on the board, one at a time, and had the teachers brainstorm words and ideas about each pic. Next, using the Earthrise photo, i gave a 5min presentation on when the picture was taken; who was involved in the photo; what is the historical context of the photo; how has the photo changed the world we live in (ie, why is it significant); how does this photo makes me, personally, feel; and how would the world be different if this event never happened?
Working in pairs the teachers were then asked to pick a photo from the selection i had printed out, along with the accompanying background info, and prepare 5min presentations using the aforementioned questions as guidelines.
In went over really well and it forced them to synthesize information in a fairly short period of time, on topics that we hadn't previously discussed.
So thanks again Leo for your helpful and always stellar lesson ideas!