Length and width are linear measurements of dimension. Length and width can be measured with a ruler. The units for dimension are centimeters. The abbreviation for centimeters is cm. 1. Use the two rulers to measure the length and width at the same time. 2. Take a picture of the rock with the two rulers. 3. Use the label tool to write the length and width on the picture. Include the correct unit (cm). 4. Record a summary of this rock. Be sure to use ruler, length, width, and centimeters.