Standard units let everyone measure the same way — no more confusion!
STANDARD UNITS are agreed-upon measurements that everyone uses. In the US Customary system, we use inches (in) and feet (ft). In the metric system, we use centimeters (cm) and meters (m). Rulers and tape measures use these units to give exact measurements.
US Customary
Metric
Both systems measure the same lengths — just with different unit sizes!
About 1 inch: Width of a thumb 👍 About 1 foot: Length of a school ruler 📏 About 1 cm: Width of a small button 🔘 About 1 meter: Height of a kitchen counter 🍳 A classroom whiteboard is about 3 meters wide!
How to use a ruler:
About how long is a real school desk? Choose the most reasonable measurement.
Remember This!
Use your body as a ruler! Your pinky finger is about 1 cm wide. Your foot (with shoe!) is close to 1 foot. Your outstretched arms span about 1 meter!