Transcript Slide 1
Years 3, 4, 5, 6 13th March 2014 1 How do you multiply and divide? 57 x 2 78 ÷ 2 43 x 50 742 ÷ 2 36 x 25 700 ÷ 4 18 x 15 65.5 10 8 x 19 17 ÷ 5 34 x 7 5.4 ÷ 6 2 Multiplication vocabulary x o groups of o lots of o times table o times o multiplied by o multiply o double 3 Mistakes children make: 76 x 8 5648 67 x 54 268 335 101 r 5 603 7 847 4 Multiplication – Grid method 47 x 8 = x 40 8 320 7 56 376 37 x 46 = x 30 7 40 1200 280 6 180 42 1480 222 1702 5 TU x TU (Long multiplication – multiplication by more than a single digit) 72 x 38 Children will approximate first 72 x 38 is approximately 70 x 40 = 2800 6 Using similar methods, they will be able to multiply decimals with one decimal place by a single digit number, approximating first. They should know that the decimal points line up under each other. e.g. 4.9 x 3 Children will approximate first 4.9 x 3 is approximately 5 x 3 = 15 7 HTU x TU (Long multiplication – multiplication by more than a single digit) 372 x 24 Children will approximate first 372 x 24 is approximately 400 x 25 = 10000 8 Using similar methods, they will be able to multiply decimals with up to two decimal places by a single digit number and then two digit numbers, approximating first. They should know that the decimal points line up under each other. For example: 4.92 x 3 Children will approximate first 4.92 x 3 is approximately 5 x 3 = 15 9 Your turn! How many legs do 36 spiders have? 82 x 43 = 34 x 3.72 = 10 Division vocabulary share o share equally o divide o divided by o groups o halve o half o 11 Division In Year 3 ... Division using an empty number line How many groups of 5 are there in 25? 25 ÷ 5 = 5 5 0 5 5 5 10 5 15 5 20 25 12 Division in Year 4 13 Chunking - We use repeated multiplication with numbers that we are confident with such as 10, 5 and 2. 14 Integers are whole numbers (positive or negative), not fractions or percentages. 15 Your turn! Try chunking with this division calculation. 144 ÷ 3 48 3 144 - 30 114 - 30 84 - 30 54 - 30 24 -24 0 x10 x10 x10 x10 x8 48 16 Children need to be able to decide what to do after division and round up or down accordingly. They should make sensible decisions about rounding up or down after division. This is needed when solving word problems eg Kate needed 56 plastic cups for her party. They came in packs of 6. How many packs did she need? 17 In Year 5 children will continue to use written methods to solve short division TU ÷ U. Children can start to subtract larger multiples of the divisor, e.g. 30x Short division HTU ÷ U 18 Progression on to long division 972 ÷ 36 27 36) 972 - 720 252 -180 72 - 72 0 20 x 5x 2x Answer 27 19 Any remainders should be shown as fractions, i.e. if the children were dividing 32 by 10, the answer should be shown as 3 2/10 which could then be written as 3 1/5 in its lowest terms. 20 Extend to decimals with up to two decimal places. Children should know that decimal points line up under each other. 21 Written methods are to be used when calculations are too difficult to be done mentally. These are some examples of calculations children should be able to do by the time of their KS2 SATs. How many sevens are there in six hundred and thirty? KS2 2008 Mental test level 4 When a number is divided by seven, the answer is three remainder four. What is the number? KS2 2007 Mental test level 5 Calculate 848 ÷ 16. KS2 2006 Paper A level 5 22 How you can support your child at home Look for and talk about numbers in the environment Play games Shopping and giving change. Number bonds for 10, 20, 100 Doubles/Halves Times tables Multiplication facts Division facts Practise adding and subtracting mentally 23 Useful websites for practising maths http://www.mathschamps.co.uk/index.php http://www.math-drills.com/division.shtml http://teachmykids.co.uk/free_resources/ http://www.bbc.co.uk/bitesize/ks2/maths/ http://www.mad4maths.com/kids/ http://resources.woodlandsjunior.kent.sch.uk/maths/timestable/interactive.htm http://www.bbc.co.uk/schools/websites/4_11/site/numeracy.shtml http://www.funbrain.com/brain/MathBrain/MathBrain.html http://www.channel4learning.com/index.html 24