Final answer:
Before opening pineapple cans, you should wash the top to avoid contamination, then use a can opener to safely open the can.
Step-by-step explanation:
Just before opening pineapple cans, it is important to ensure safety and cleanliness. To prevent the contents from being contaminated, wash the top of the can first. After cleaning, you can use a can opener to open the can. Contrary to the method described for experimenting with sound transmission using cans and a string, opening a can of pineapple involves no need for toothpicks or strings. This prior cleaning step is essential to remove any dust or bacteria that could enter the can once opened.