# Chapter 8 The Metric & Imperial Systems of Length, Weight and Capacity

CHAPTER 8

THE METRIC AND IMPERIAL SYSTEM, OR LENGTH, WEIGHT AND CAPACITY

The metric system was introduced to the UK in the 1970s, after we joined the EEC (European Economic Community). Membership of the EEC was ratified in a referendum, and I do wonder if there would have been a ‘yes’ vote if the public had been made aware that, as part of the deal, we would be signing up to metrification of weights and measures within 5 years of joining. The old imperial system is heavily ingrained in our culture, and the UK seems to lack the political will, not to mention the fiscal requirement, of making a complete switch. Consequently we are running with two systems, and the native population is, in the most part, as confused as anyone else.

When I teach this topic, whether in ESOL maths or FS maths sessions, I deal with each part separately and in different lessons, as there is a lot for learners to assimilate. I always use kinaesthetic or hands on activities to teach the subject and to check learning. Most measuring equipment in the UK has both systems on, and it is vital for learners to be clear about what each system looks like to make sense of it. I also get a comparison up on the board early on in the lesson using learners' existing knowledge and filling in the gaps, so learners are sharing what they do know.

Many ESOL learners will have used the metric system before, and may have a fuller system than we use, for instance in some countries they have named units of measure for 20, 30, 40 and 50 centimetres and centilitres. Everyone in the UK is exposed to the old imperial system as distances are still in miles, milk and beer are still bought in pints and many people of all ages still weigh themselves in stones and pounds. That will be pounds in weight, not in money, and it is written lb, not £. Not confusing at all really!

I do feel that cost has been a major factor in our apparent stall on metrification. For instance, it is fairly simple to add the metric system to measuring tapes, weighing scales and kitchen jugs, but the cost of converting all the road signs to kilometres, both those relating to speed limits, and the distances between destinations, all the cars' odometers from miles to kilometres, and then re-educating a resistant public must have looked prohibitive. Equally, all the pint milk bottles and glasses should have been replaced, which would have been an enormous waste of resources.

The following charts show how the systems look for each topic, and there are some comparisons to give learners a feel for what the imperial system looks and feels like. Luckily, there are some close comparisons: a yard is almost the same as a metre, perhaps because they are both based on a stride, a metric tonne is virtually the same as an imperial ton, a blessing for the transport industry, which could have had a very difficult time otherwise, and a pint is about 10% bigger than half a litre.

The Metric And Imperial Systems Explained

Notes: Abbreviations are shown after the full words. It is safer not to shorten ‘mile’ as it confuses it with metric abbreviations. Only common imperial units of measure shown.

For ESOL learners it will often be necessary to teach the vocabulary that precedes the actual measuring, such as length, width, height, and how these words are used either in descriptions, or in answer to questions such as ‘How long is the car?’. The language changes as lengths increase, i.e. we ask how far it is between two places, and use words such as distance to describe that relationship. Much of this language will emerge as you and the learners are working on these topics, and it is often useful to get a list up and let learners translate into their first language to help them remember. At a recent conference I heard of a primary school that is decorating the walls of the classrooms with maths words translated into the first language of the children; what a good idea to show how we value other languages and cultures, and to increase the confidence of the learners, as well as helping learning.

Additionally in ESOL maths classes you will need to name all the equipment in use, which is just the kind of activity that can be forgotten for ESOL learners, as when teaching native English speakers we take knowledge of all that vocabulary for granted.

Lessons on the metric and imperial systems are an ideal opportunity for teaching or revisiting comparatives and superlatives, and it works for measuring lengths, weights and capacities. For instance, I might ask a group, usually in pairs, to measure the length of five objects, then as an extension for early finishers, ask them which object is the longest, which is the shortest? You could then ask them which object is the heaviest, which is the lightest? Is the longest object also the heaviest? This work can then be discussed with the whole group.

Capacity

Capacity is the one that most often fools people; we tend to believe that the tallest container will hold the most, but this is often a marketing ploy and not the case at all, which can be a revelation to both native English speakers and ESOL learners. In addition to helping your learners with English you might turn them into savvy shoppers! For me this lesson involves water, and you will need some one litre cubes to show learners the basis of the metric system.

Basis of the Metric System

The metric system is based on plain water, as this is the one universal wherever you go in the world. A one litre cube measures ten centimetres by ten centimetres by ten centimetres, so its volume is 10 x 10 x 10 = 1000 cubic centimetres. This cube holds one litre of water and the weight of that water is one kilogram. You have to admit that it is very clever! It is also very memorable to learners, as when you hand them a jug or bottle containing a litre of water, because it is so much taller than the cube most people think the water won’t fit in, they are on tenterhooks whilst the pouring is going on!

Latin Roots

The other aspect I show learners is how the language is derived from Latin, as many languages have Latin roots:

• ‘milli’ means thousandths so there are 1000 millimetres in a metre, 1000 milligrams in a gram and 1000 millilitres in a litre;

• ‘centi’ means hundredths so there are 100 cm in a metre and 100 cl in a litre.

• ‘kilo’ represents thousand, so there are 1000 metres in a kilometre, and 1000 grams in a kilogram.

• Learners may know other words that sound similar that will prompt discussion, such as millennium and century, or they can be encouraged to look for similar words in a dictionary.

As you can see from the table showing metric imperial comparisons and equivalents, this is also a useful topic to teach or revisit the language of approximation and estimation, a topic that not all learners or cultures find very easy but which is tested from Entry 3 upwards in FS Maths exams.

Up to Level 1 FS and Adult maths learners will need to know all the metric equivalents, such as 100 cm is a metre; at Level 2 and GCSE Maths learners will also be asked to do conversions between the two systems, but they will always be given a conversion rate for this, such as ‘there are 2.5 cms in a foot, how many centimetres in 3 feet?’ No-one expects anyone to remember the imperial equivalents, such as the number of ounces in a pound, and these will always be given if needed for an answer.

JMS 2013/14