context: When it was time to clean the floor, the first thing I needed to do was sweep the debris and garbage. I use the broom to sweep the floor from one end to the next, piling all of the dust, dirt and other debris on the floor into a pile in the center of the room. I used a dustpan to collect all the debris, placing it on the floor and using the broom to sweep all of the brie onto the surface of the dustpan. I empty the contents of the dustpan into the garbage then placed the broom and dust pan into the corner. I then made a bucket of water that had floor cleaning solution diluted into it in order to make sites. I took my mop from the corner of the room where the room was, and placed the head of the mob into the water, soaking the head of the mop. Once the head of the mop was completely submerged underwater, and soaking wet, I removed the mop from the bucket and squeeze out the excess water. I then use the mop to wipe over the entire floor. I ensure that all of the stains and stuck on dirt that was on the floor have been removed with the mop, and that the floor looks spotless including when I finished. I rinsed off the mop with clean water, to remove the left over grime and dirt, and placed the mop in the corner. I also emptied the dirty mop water from the bucket, and placed the empty bucket in the corner as well. I then left the room so that the floor could completely dry before I stepped on it again.
question: Why did they start by sweeping?
reference: It's the first step to cleaning the floor.
candidate: they wanted to clean the floor.