As Amazon pushes forward with robots, workers find new roles

Scott, an Amazon worker, watches her replacement - a giant, yellow mechanical arm - do the stacking

Nissa Scott started working at the cavernous Amazon warehouse in southern New Jersey late last year, stacking plastic bins the size of small ottomans. It was not, she says, the most stimulating activity. And lifting the bins, which often weigh 25 pounds each, was also tiring over 10-hour shifts.

Now Ms. Scott, 21, watches her replacement — a giant, bright yellow mechanical arm — do the stacking.

Her new job at Amazon is to babysit several robots at a time, troubleshooting them when necessary and making sure they have bins to load. On a recent afternoon, a claw at end