earthing up potato shoots

Hi all, another quick question,any advice much appreciated. I am growing spuds in grow bags and have my first shoots appearing. All my books suggest piling a mound of soil around these shoots to earth up. Does this mean completely covering up these shoots by piling compost on top of them so that they are completely hidden?

I've grown spuds in 2 dustbins this year. I let the shoots grow about an inch out of the soil and then totally covered them with soil. When the soil level got to about 6 inches below the top of the bin I stopped earthing them up and now the plants are about 12 inches high.