The YP's must point out on a map a variety of places in their local area. They should then work out the 6 figure grid reference for each of these places.
Street map, list of places, list of grid references for these places
Give each patrol a street map of the local area, and a list of places of interest in the area such as doctors, schools, vets etc etc. The scouts should use the map to work out the 6 figure grid references to each of these places.