Docstoc

ratio_proportion

Document Sample
ratio_proportion Powered By Docstoc
					                                      Ratio and Proportion

Solve simple problems involving ratio and proportion:
         using ‘real life’ contexts, such as money to contextualise problems
         modelling calculations with real objects such as beads

The concept needs to be modelled in order for children to develop clear mental images. The two
lessons on ratio and proportion in ‘More Numeracy Lessons’ (Y6, p 96 – 99) offer sound contexts
within which children can develop such images.

Related mental/oral starters – practise doubling, trebling numbers and continuing sequences.

Contexts for discussing ratio and proportion:
           Mixing ingredients – paints to get the right shades
           Recipes - making cakes, biscuits
            - calculating cooking time/kg
           Boys and girls in class/swimming club etc
           Scale – on maps
            - plans of buildings
            - models
           Foreign exchange – 10 francs for every pound
           Colours of things – counters, cubes, necklaces, Smarties (30% blue, 3 out of 10, 3/10, 0.3,
            3 for every 7 others)
           Fruit bowl – two apples for every three oranges
           Purse – three copper for every eight silver coins
           Crisps – two packets plain for every five flavoured
           Tile patterns
           Make a play kitchen for Reception
           Doll survey - which approaches the human ratio 1:7, head: body
           Compare toys – the toy tiger is much bigger than the toy elephant, not the same
            proportions as in real life
           Money - A favourite aunt decides to give her nephew and niece £120 between them. But
            because the niece is the older of the two, she says that the money must be divided so
            that she gets £3 for every £2 that her brother gets. How much does each child get?
           Distance – 5 miles is the same distance as 8 kilometres. If I walk for 10 miles, how many
            kilometres have I travelled. Encourage the children to use systematic recording, e.g. 5
            miles = 8 kilometres, 10 miles = 16 kilometres
           School trip – there are 49 people altogether. For safety there is 1 adult for every 6
            children. How many adults go on the trip?
           Manufacture – a machine making CDs produces one faulty CD in every 1000 it makes. At
            the end of the day it made one million CDs. How many faulty CDs has it produced?
           Ingredients – sugar, fat and fibre per 100g in one product, compared to sugar, fat and
            fibre per 25g in another product
           Time – two days off for every five days at school, six hours at school for every 18 hours
            not at school


    Numeracy in Leicestershire                                                                 JEH

				
DOCUMENT INFO