Aim To explain some of the strategies that we use to teach +, -, x and ÷. • Concrete/practical/objects • Pictorial • Abstract (‘writing it down’) • We always try to relate calculations to real-life and to solving problems • Mental as well as pencil-and-paper methods • Develop rapid, confident recall of number facts and Times Tables • • • • Add Plus More than Count on Addition Laying the foundations…… • • • • • • Number lines Practical equipment Multilink cubes Real life contexts Number bonds Patterns Use of a number line 6+5= 1 2 3 4 5 6 7 8 9 10 11 12 13 Use of a 100 square 34+14 = Partitioning…….. • Place value • Partitioning • Recombining Children use their knowledge to move towards the ‘standard’ written method: • Continue to use partitioning • 58 + 43 50 + 8 40 + 3 90 + 11 = 101 Column addition…. • The final step, when the children have a sound grasp of place value & of the whole process… 364 + 54 418 1 Subtraction Subtraction Taking away practically. 3-2= Use of a number line/100 square 12-6=6 1 2 3 4 5 6 7 8 9 10 11 12 13 Written methods for Subtraction Partitioning Subtraction can be recorded using partitioning to write equivalent calculations that are easier to carry out mentally. For 74 - 28 this involves partitioning the 28 into 20 and 8, then subtracting 20 and 8 in turn. 74 – 28 is the same as 74 – 20 – 8 74 – 20 = 54 54 – 8 = 46 Written methods for Subtraction Stage 4: Column method The expanded method is eventually reduced to: Multiplication Multiplication- repeated addition 3x5= (3 groups of 5) xx xx x 5 xx xx x + 5 xx xx x + 5= 15 Arrays Children should be able to model a multiplication calculation using an array. This knowledge will support with the development of the grid method. 3x5 5x3 Grid Method Using partitioning, we can look at 8 x 13 = 104 as 8 x 10 plus 8x3: 80 + 24 = 104 Standard Written Method Division ÷ Written methods for Division Initially division is introduced as ‘sharing’ using real objects or pictures. Share 10 apples equally between 2 children which eventually becomes 10 ÷ 2 = 5 • Remainders: Written Methods for Division • ‘Short’ division Written methods for Division Long division for HTU ÷ TU The next step is to tackle HTU ÷ TU. This is the 'long division' method. The 20, or 2 tens, and the 3 ones forming the answer are recorded above the line, as in the second version.
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