# Grade 10-12 Mathematical Literacy (Measurement)

Introduction

Welcome Class to our Webquest lesson of today.

Measurement plays a massive part in each and everyday's activities. In everyday life it is often neccessary to convert units of measurement. Lengths and distances measured in the metric system can be converted to larger or smaller units by multiplying or dividing by tens, hundreds or thousands. Units of capacity and units of mass are converted by multiplying or dividing by 1 000.

Question like the following can be ask to test learners knowledge and understanding of the topic.

Do you remember how many centimetres there are in a metre?    100

a kilometre is a thousand thimes bigger that a metre.

There are 1 000 millilitres in a litre?

Also that a milligram is 1 000 times smaller that a gram.

Converting linear units into metric are as follow.

 10 millimetres (mm) 1 centimetre (cm) 10 centimetres (cm) 1 decimetre (dm) 10 decimtres (dm) 1 metre (m) 10 metres (m) 1 decametre (Dm) 10 decametres (Dm) 1 hectometre (hm) 10 hectometres (hm) 1 kilometre (km)

NB: The following sentence is useful for remembering the prefixes of linear units in the metric system:

"King Henry died of a miserable disease called measles."

 King Henry died of a Miserable Disease Called Measles kilometre hectometre decametre metre decimetre centimetre millimetre km hm Dm m dm cm mm

Converting from larger units to smaller units. For example:  kilometre to metres, you multiply by 10 for every unit.

Example:

Convert 1,452km to m, you are changing to a smaller unit and so you multiply by ten for every unit.

1,452km x 10 x 10 x 10 = 1,452 x 1 000m

= 1 452m

 km hm Dm m dm cm mm 1, 4 5 2 1 4 5 2, 0

Converting from smaller units to larger units. For example:millimetres to metres, you divide by 10 every unit.

 km hm Dm m dm cm mm 1 2 5, 0, 1 2 5

So when converting 125mm to m you are changing to a larger unit so you divide by ten for every unit. Remember that 125mm can be written as 125,0mm? In the table above you will see the comma after the 5 in the mm column. To divide by10 you move the comma one place to the left. But in this question we move the comma 3 places to the left because to convert to metres you divide by 10 three times.

125mm ÷ 10 ÷ 10 ÷ = 125 ÷ 1000m

=0,125m

1 000 millimetres(ml) = 1 litre

In real life we usually only need to convert between millimetres, ventimetres, metres and kilometres.

10mm = 1cm

100cm = 1cm

Converting units of mass in the metric system

Units we use when working with mass are gram, kilograms and tonne. In the metric a tonne (t) sometime called a metric ton is a unit of mass equal to 1 000kg.

 1 000g 1kg 1 000kg 1t

Learner can Watch the following video, of conversion of measurement.

Process

Activity 1: Converting linear units

(a) Convert 1,25m to mm.

(b) Convert 5 219m to km.

(c) The front wall of sipho's house measures 855cm. How long is this in m?

Activity 2: Converting units of capacity

(a) Convert 500ml to litres

(b) Convert 3,5l to ml

(c) Amy poured 1 750ml juice  into a large measuring jug. How many litres did she have?

Activity 3: Converting units of mass

(a) Convert 134g to kg

(b) Convert 0,5kg to g

(c) Santie bought 3 packets of flour which each weighed 2,5 kg

(i) How many kg of flour did she buy

Activity 4: Converting spoons and cups to ml

(a) Convert 3 cups to ml

(b) Convert 25tsp to ml

(C) Jean needs 45ml of oil for frying her cabbage. She only has a tablespoon with which to measure. How many tablespoons of oil does she use?

Evaluation

Memorandum

Activity 1: Converting linear units

(a) 1,25m x 1 000 = 1 250mm

(b) 5 219mm  ÷ 1 000 = 5,219km

(c) 855  ÷ 100m = 8,5 m

Activity 2 : Converting units of capacity

(a) 500ml  ÷ 1 000 = 0,5l

(b) 3,5l x 1 000 = 3 500ml

(c) 1 750ml  ÷ 1 000 = 1,75l

Activity 3: Converting units of mass

(a) 134g  ÷ 1 000 = 0,134kg

(b) 0,5kg x 1 000= 500g

(c) (i) 3 x 2,5kg = 7,5kg

(ii) 7,5 kg x 1 000 = 7 500g

Activity 4: Converting spoons and cups to ml

(a) 1c = 250ml

3c = 750ml

(b) 1 tsp = 5ml

25 tsp = 5 x 25ml

= 125ml

(c) 15ml = 1 Tbsp

45ml = 1 x (45/15 Tbsp)

= 3 Tbsp

Conclusion

By the end of this lesson learners should by able to convert and perform calculations with the following units of measurement and time:

• linear units in the metric
• units of capacity to metric
• units of mas to metric
• units of measurement using conversion factors and tables
• units of time in various formats.
Credits

Mathematical Literacy grade 10, 11 & 12 book

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