Name: Date:

1.2 Measuring LengthHow do you find the length of an object?

Reading the meter scale correctly

Look at the ruler in the picture above. Each small line on the top of the ruler represents one millimeter. Larger lines stand for 5 millimeter and 10 millimeter intervals. When the object you are measuring falls between the lines, read the number to the nearest 0.5 millimeter. Practice measuring several objects with your own metric ruler. Compare your results with a lab partner.

Stop and think a. You may have seen a ruler like this marked in centimeter units. How many millimeters are in one

centimeter?

b. Notice that the ruler also has markings for reading the English system. Give an example of when it would be better to measure with the English system than the metric system. Give a different example of when it would be better to use the metric system.

Size matters! When you describe the length of an object, or the distance between two objects, you are describing something very important about the object. Is it as small as a bacteria (2 micrometers)? Is it a light year away (9.46 × 1015 meters)? By using the metric system you can quickly see the difference in size between objects.

Materials• Metric ruler• Pencil• Paper• Small objects• Calculator

Page 2 of 4

Example 1: Measuring objects correctly

Look at the picture above. How long is the building block?

1. Report the length of the building block to the nearest 0.5 millimeters.2. Convert your answer to centimeters. 3. Convert your answer to meters.

Page 3 of 4

Example 2: Measuring objects correctly

Look at the picture above. How long is the pencil?

1. Report the length of the pencil to the nearest 0.5 millimeters. 2. Challenge: How many building blocks in example 1 will it take to equal the length of the pencil?3. Challenge: Convert the length of the pencil to inches by dividing your answer by 25.4 millimeters per inch.

Example 3: Measuring objects correctly

Look at the picture above. How long is the domino?

1. Report the length of the domino to the nearest 0.5 millimeters. 2. Challenge: How many dominoes will fit end to end on the 30 cm ruler?

Page 4 of 4

Practice converting units for lengthBy completing the examples above you show that you are familiar with some of the prefixes used in the metric system like milli- and centi-. The table below gives other prefixes you may be less familiar with. Try converting the length of the domino from millimeters into all the other units given in the table.

Refer to the multiplication factor this way:

• 1 kilometer equals 1000 meters.

• 1000 millimeters equals 1 meter.

1. How many millimeters are in a kilometer?

2. Fill in the table with your multiplication factor by converting millimeters to the unit given. The first one is done for you.

3. Divide the domino’s length in millimeters by the number in your multiplication factor column. This is the answer you will put in the last column.

1000 millimeters per meter × 1000 meters per kilometer = 1,000,000 millimeters per kilometer

1000 millimeters per meter × 10–12 meters per picometer = 10–9 millimeters per picometer

Prefix Symbol Multiplication factor

Scientific notation in meters

Your multiplication factor

Your domino length in:

pico- p 0.000000000001 10–12 10–9 pm

nano- n 0.000000001 10–9 nm

micro- µ 0.000001 10–6 µm

milli m 0.001 10–3 mm

centi- c 0.01 10–2 cm

deci- d 0.1 10–1 dm

deka- da 10 101 dam

hecto- h 100 102 hm

kilo- k 1000 103 km