Final answer:
When a food handler drops a bimetallic stemmed thermometer on the floor, they should discard it and use a new one.
Step-by-step explanation:
When a food handler drops a bimetallic stemmed thermometer on the floor, they should not continue using it. The thermometer could have been damaged or contaminated by the floor, which poses a risk for food safety. The food handler should discard the thermometer and use a new one to ensure accurate temperature readings and maintain the hygiene standards in food handling.