1. The document discusses the history and development of systems for measuring length and distance, from early rulers based on body parts to the modern metric system.
2. It describes how the metric system was developed using the distance from the Earth's equator to the North Pole, divided into 10 million equal parts called meters.
3. The document provides examples of measuring various lengths in millimeters and centimeters using a metric ruler, and explains how the metric units of meters, centimeters and millimeters are used to measure different distances.