Identify the ruler type (inches, centimeters, or both)
Check the smallest marks (each smallest division equals 1 unit of that scale)
Decide the measurement units you need (inches or centimeters)
Align the object’s left end (or one reference edge) with the 0 mark
Read the value at the object’s right end where it lines up with a tick mark
If the end falls between ticks, estimate to the nearest fraction shown by the ruler
For inches, use the subdivisions (e.g., 1/16 in marks) to estimate the fractional part
For centimeters, use millimeter subdivisions (10 mm = 1 cm) to estimate the fractional part
Record the measurement with the correct unit (e.g., 3.5 cm or 1 7/8 in)
Double-check by ensuring the measurement starts at the intended reference mark and is read from the correct end