…London. Education Following on from his MapRoulette tutorial, Martijn van Exel continued with an explanation of MapRoulette’s cooperative challenges. They involve collaboration between a challenge owner, providing the proposed OSM changes, and you, validating, tweaking and committing them to OSM. Cooperative challenges are ideal for when you may be thinking… (Search hits: 2 in body, 0 in title, 0 in categories, 0 in tags, 0 in other taxonomies, 0 in comments. Score: 4.24)