GCSE MATHSSession 19 – Measures

Length - cm, metres, km, inch, feet, miles

Mass (weight) - kg, pounds, ounces

Capacity (volume) – litres, gallons cm3

Metric units

Kilo…

Centi…

Milli….

When converting between metric unit we multiply or divide by 10, 100 or 1000

Converting area and volume How many cm3 in 1m3?

Ex31.1 Q 7, 8, 11, 16 and 19

Estimation using ‘common sense’ The degree of accuracy is determined by

what we ae measuring.

Heights of mountains are not measured to the nearest mm, or even nearest cm.

Time in the Olympics is recorded to 1/100 of a second

EX31.2 Q 1 and 6 through discussion

Imperial measures

1 foot = 12 inch 1 yard = 3 feet

1 pound = 16 ounces 14 pounds = 1 stone

1 gallon = 8 pints

Conversions to remember (approximate)

1 mile = 1.6 km (8/5 = 1.6) (km is shorter) 1 inch = 2.54 cm 1 foot = 30 cm (think of a ruler)

1kg = 2.2 pounds

1 pint = 568ml or 1l = 1.75 pints 1 gallon = 4.5l

Ex31.3 – 10 mins

Discrete and continuous data Continuous data is measured and can

take any value (it depends on the degree of accuracy you measure to)

Discrete data only takes certain values. eg the number of people or a shoe size or ice skating score

Upper and lower bounds If continuous measure (c) is recorded to the

nearest x then the limits of possible values for c are:

C For example

18cm (recorded to the nearest cm)

Lies between 17.5cm and 18.5cm

Although it could never be 18.5cm, but it could be 18.4999999999999999999999999999999cm

Calculating using upper and lower bounds Example page 333

Try a few from 31.5

Dimensions Length, area, volume how many dimensions

If a b and c all represent length, they can all be replaced by L

Length – 1 dimension = L Area - 2 dimensions = L2

Volume - 3 dimensions = L3

Any formula that cannot be simplified down to one of these can be called ‘inconsistent’ as it does not represent length, area or volume (see example d page 335)

Any time at the end go through BKSB

Encourage everyone to begin their revision of topics covered

Homework

Use BKSB to revise topics

Produce a revision page for the geometry ‘what you need to knows’

Including 2D shapes, 3D shapes and circles