I have a puppy that poos outside in the garden. However, she is not selective in the location where she poos, and the garden is relatively large. This makes the weekly clean up a bit of a scavenger hunt, and it's easy to miss one or two, which makes walking on the garden a little less pleasant. It would be easier for us if she went to the toilet in a more limited region of the garden.
What is a good strategy for training a dog to poo in a particular part of the garden?