Final answer:
The first step when collecting a stool sample is to gather the necessary materials and collect a small sample of the stool using a scoop or stick.
Step-by-step explanation:
The first step when collecting a stool sample is to gather the necessary materials, such as a clean collection container, gloves, and a small scoop or stick. Then, using the scoop or stick, collect a small sample of the stool and place it into the collection container.