Overview
This lecture covers how to read measurements using a ruler, understand tick mark values, and record measurements with estimated digits.
Understanding the Ruler
- Examine the ruler to determine the value and unit of each tick mark.
- The main numbered tick marks on this ruler represent centimeters (cm).
- Each large graduation equals 1 centimeter, while smaller tick marks represent 0.1 centimeters.
Measuring Length Accurately
- Identify where the object's edge lies relative to the numbered tick marks.
- State the value as greater than one tick mark and less than the next (e.g., greater than 2 cm but less than 3 cm).
- Record the measured value up to the smallest marked unit confidently (e.g., 2.5 cm if on a tick mark).
Estimating Beyond the Smallest Unit
- If the measurement falls between two tick marks, estimate an extra digit (the estimated digit).
- Example: If the line is between 2.5 and 2.6 cm, estimate as 2.55 cm.
- The first digits are read directly from the ruler; the last digit is estimated.
Key Terms & Definitions
- Graduation — a mark on a measuring instrument showing a fixed interval (e.g., each tick on a ruler).
- Estimated Digit — the final digit in a measurement that is not exactly marked but is approximated by the observer.
Action Items / Next Steps
- Practice reading measurements from a ruler, including estimating the last digit.
- Review the units and graduation intervals on your ruler before using it.