I'm with a woman and her son (or daughter) who is aged about 12. We have the task of doing a 'stock take' in a large rambling empty multi-storey factory or warehouse. It is like a disused victorian factory that has been converted into a warehouse - with storage shelves lining the walls. To get from one floor to the next you have to climb up ladders, or in some cases, just pull yourself up through a hatch. The stock we are supposed to be counting is large jars or packets of jam or dried milk or something. I have to estimate how many packets there are, because we don't have time to count them. We also don't have pen and paper so I have to keep the numbers in my head - an almost impossible task.