Measuring, Estimating and Units

Hong Kong

Stage 1 - Stage 3

Lesson

As we have been learning, everything in maths that relates to the ‘real world’ has units. If there is a point to it there are units attached to it. The units that we use are particular to what we are measuring. Being able to measure reasonably and correctly, whether that is lengths, volumes, mass or even the number of people at an event revolves around being able use the correct and most appropriate units.

The units we need to know about formally are

LENGTH/DISTANCE --> *mm, cm, m, km *

AREA --> *mm ^{2} , cm^{2}, m^{2}, km^{2} *

VOLUME -->* mm ^{3}, cm^{3}, m^{3}, km^{3}*

CAPACITY --> *mL, L, kL, ML*

WEIGHT (actually called MASS) --> *mg, g, kg, metric ton*

TIME --> *seconds, mins, hrs, days, weeks, months, years *

One way we can identify the most appropriate unit is to find items or objects you are familiar with and know their approximate lengths or weights or volumes.

**Choose**: Which is the most appropriate unit to measure the length of a pencil? millimetres, centimetres or metres.

**Think**: Think about lengths that I know. I know:

that my pencil leads are measured in millimetres

that my phone is about $15$15 cm long and

that my height is about $1.6$1.6 m

I would connect the length of a pencil to being closest to my phone, rather than my pencil lead or my height.

**Do**: I will say that **centimetres **is the most appropriate unit to measure a pencil.

Choose the most appropriate unit of measure for the height of a tree.

Metres

AKilometres

BCentimetres

C

Choose the most appropriate unit of measure for the area spanned by a bathroom wall.

Square metres

AHectares

BSquare centimetres

C

Which of the following is it most appropriate to measure in cubic centimetres?

The area of a sheet of paper

AThe volume of air in a hall

BThe volume of an empty bottle

C