The Darien Gap serves as one of the largest geographical mysteries of the 20th century. Stretching from the tip of Alaska to the end of Argentina there is a 48,000 km Pan-American Highway. This continuous stretch of roadway holds a record for being the longest motor-able road, but there is a gap - an area of tropical forest that remains disputed.
The dispute is simple, should the highway continue through the tropical forest or should the gap (forest) remain. After reading through the passage from BBC News Magazine, and perhaps the entire article explaining the Gap, have students create a postcard, taking a stance and defending whether or not the Gap should remain.
I have used this briefly as a one day class assignment, though after seeing the students excitement, could have easily made this a 2-3 day activity tying together other environmental issues or human environment interaction.
Rather than a postcard, this could be done as a persuasive essay or presentation as well - depending on the amount of time you have to devote to the assignment.