Grade 5 · Unit 5: Using units of measurement

Length and perimeter

Convert and calculate with decimals.

A running track is 400 m around.

Running track

One lap of a track is 400 m. How many laps make 2 km? 2 km = 2000 m; 2000 ÷ 400 = 5 laps.

Converting with decimals

× 10, × 100, × 1000 to smaller units. ÷ 10, ÷ 100, ÷ 1000 to bigger units. 17.5 cm = 175 mm = 0.175 m.

Compound shapes

This shape is 7 wide and 4 tall. Missing sides: 7 − 3 = 4 and 4 − 2 = 2. Perimeter = 7 + 2 + 4 + 2 + 3 + 4 = 22 units.

Circles

The perimeter of a circle is the circumference. It is about 3.14 times the diameter. A rickshaw wheel of 50 cm diameter moves about 1.57 m each turn.

Miles and inches

The UK and USA still use miles on road signs. Screens and TVs are measured in inches: a 40-inch TV is about 100 cm across. 5 miles is about 5 × 1.6 = 8 km.

What I learnt