Try to say as little as possible when introducing this task. When the group or class has finished it would be good to discuss the different approaches that pupils used.
Tell me what you first thought would be a good way of doing this.
Tell me about any difficulties you encountered when solving this challenge.
Although unrelated to the challenge you might like to make use of these maps to discuss why the 'straight' lines of the 'as the crow flies' are drawn as various curves.