The brood emits a pheromone that says "feed me, I need protein" which is why the workers put pollen as close to the brood as possible - i.e. in an arc around it, or possibly on the frame next the brood. (As you work into the frames you'll often see a frame of pollen and then know that the next frame will have brood in it. Othertimes there will be brood on the back of a pollen frame which the queen has laid before the pollen is consumed or moved out of the way and she lays the inner-most side). Some bees get more pollen than others. If the first super has an arc of pollen and within (below) it there are some empty cells, that usually indicates that the bees don't have enough space for brooding as they have cleared the super space for the queen to lay in, not realising that she can't get through the excluder.
May your bees read the same books as you do.