Measuring Length

Measuring Length

Centimetres & Millimetres

Measuring Length

• We use rulers to measure small lengths

• Rulers use centimetres and millimetres

Multiple Choice

How many millimetres are in 1cm?

• 1

• 10

• 100

***The printable ruler is on the Google Classroom assignment***

Measuring Length

• You can use millimetres to measure the length, width, height, or thickness of small objects.

• A dime is about 1 mm thick.

Measuring Length

• This pine needle is about 6 cm long.

• To be more precise, you read the length in millimetres.

• The pine needle is 62 mm long.

Measuring Length

• One millimetre is one-tenth of a centimetre.

• The pine needle is 6.2 cm long.

• So, you can also read the length of the pine needle in centimetres.

• You say: 6 and 2 tenths centimetres

Use this for the next slide

Multiple Choice

How long is this pencil?

• 14 mm

• 14 cm

• 14 m

Use this for the next slide

Multiple Choice

How long is this eraser?

• 52 cm

• 5.2 cm

• 52 m

• 5.2 mm

Referents

• We use referents to quickly estimate length

• Your little finger is a good referent for a centimetre (cm)

• The width of your door is a good referent for a metre (m)

Multiple Choice

What is a good referent for a metre?

• The width of a doorway

• The width of your little finger

Multiple Choice

What is a good referent for a centimetre?

• The width of a doorway

• The width of your little finger

Converting

• You need to multiply or divide when you are converting between different metric units

• The picture on the right is very clear

Multiple Choice

Which is equal to 105 cm?

• 1.05 m

• 105 m

• 1.05 mm

• 1.05 km

Multiple Choice

Which is equal to 5 m?

• 500 cm

• 500 mm

• 5 mm

• 5 km

Multiple Choice

Which is equal to 1 km?

• 100 cm

• 1000 mm

• 1000 m

• 10 m

Multiple Choice

Which is equal to 38 cm?

• 3.8 m

• 380 mm

• 3.8 mm

• 38 cm

Multiple Choice

Which is equal to 2 m?

• 200 cm

• 200 mm

• 20 mm

• 2 km

Multiple Choice

Which is equal to 3 km?

• 300 cm

• 3000 mm

• 3000 m

• 3 m