Introduction to Length

Show your work for each problem.

1.
Which unit would you use to measure the length of a pencil?
1. a)Meters
2. b)Kilometers
3. c)Centimeters
4. d)Miles
Answer: Centimeters
Centimeters are perfect for measuring small objects like pencils (about 15-20 cm). Kilometers and miles are for long distances, and meters are for larger objects.
2.
How many centimeters are in 1 meter?
1. a)50
2. b)1000
3. c)10
4. d)100
Answer: 100
There are 100 centimeters in 1 meter. The prefix 'centi' means hundredth, so a centimeter is one hundredth of a meter.
3.
How many millimeters are in 1 centimeter?
Answer: 10
There are 10 millimeters in 1 centimeter. Since there are 100 cm in 1 m and 1000 mm in 1 m, we have 1000 ÷ 100 = 10 mm per cm.
4.
Convert 3 meters to centimeters.
Answer: 300
centimeters. To convert from meters to centimeters, multiply by 100.
5.
Which is longer: 50 cm or 1 meter?
1. a)50 cm
2. b)They are equal
3. c)Cannot compare
4. d)1 meter
Answer: 1 meter
1 meter = 100 cm. Since 100 cm > 50 cm, 1 meter is longer than 50 cm.
6.
A bookshelf is 150 cm tall. How many meters is that?
Answer: 1.5
meters. To convert from centimeters to meters, divide by 100.
7.
Which unit would you use to measure the distance from your home to school?
1. a)Millimeters
2. b)Centimeters
3. c)Meters
4. d)Kilometers
Answer: Kilometers
Kilometers are best for measuring longer distances like the trip to school (usually 1-5 km). Meters would give very large numbers, and mm/cm are for small objects.
8.
A swimming pool is 25 meters long. Sarah swims 4 lengths. How many meters did she swim?
Answer: 100
1. How long is one length of the pool? 25
2. How many lengths did Sarah swim? 4
3. Calculate: 25 × 4 = ? 100
9.
How many meters are in 2.5 kilometers?
Answer: 2500
meters. The prefix 'kilo' means thousand.
10.
A desk is 120 cm wide. A room has a space that is 1.5 m wide. Does the desk fit?
Answer: yes
1. Convert 1.5 m to cm. What is 1.5 × 100? 150
2. The desk is 120 cm and the space is 150 cm. Is 120 < 150? yes
3. Does the desk fit in the space? yes
11.
Which of these is NOT a metric unit of length?
1. a)Centimeter
2. b)Meter
3. c)Foot
4. d)Kilometer
Answer: Foot
Foot is an imperial unit, not metric. Meter, centimeter, and kilometer are all metric units based on the meter.
12.
A marathon is 42 km and 195 m. How many meters is that in total?
Answer: 42195
1. Convert 42 km to meters. What is 42 × 1000? 42000
2. Add the extra 195 meters. What is 42000 + 195? 42195
13.
A rope is 4.5 meters long. If you cut off 75 cm, how many centimeters remain?
Answer: 375
4.5 m = 450 cm. Then cm remain.
14.
Tom runs 800 m in the morning and 1.2 km in the evening. How many kilometers did he run in total?
Answer: 2
1. Convert 800 m to km. What is 800 ÷ 1000? 0.8
2. Add the two distances: 0.8 km + 1.2 km = ? 2
15.
Which statement about metric prefixes is correct?
1. a)Kilo means thousand
2. b)Centi means thousand
3. c)Centi means ten
4. d)Milli means hundred
Answer: Kilo means thousand
Kilo means thousand (1 km = 1000 m). Milli means thousandth (1000 mm = 1 m). Centi means hundredth (100 cm = 1 m).
16.
A ribbon is 2 m and 35 cm long. Express this length in centimeters only.
Answer: 235
1. Convert 2 m to cm. What is 2 × 100? 200
2. Add the extra 35 cm. What is 200 + 35? 235