Question

Each student aligns the edge of the object with the left edge of the ruler and records a length of 4.6 cm. Which statement describes the data they collect?

Answer 1

If they align the object at the very edge of the ruler, the measurement in inaccurate. They would have to start the measurement at 0 to get an accurate measurement. When starting at the very edge, you are not taking into account the little bit of the ruler and it between the edge of the ruler and the 0 marker.
Some people start at the 1 cm mark (and then subtract 1 from their raw measurement) to make sure they have the most accurate measurement they can get.
I'm pretty sure that is what you are talking about. Hope this helps!!