Adio a Thynnu Addition and Subtraction CA 2KS
Adio a Thynnu Addition and Subtraction CA 2/KS 2 Cymraeg Saesneg S 2. 1 S 2. 2 S 2. 4
DARLITHOEDD DIWETHAF TASG CYCHWYNNOL 1) Disgrifiwch beth yw’r gwahaniaeth rhwng data arwahanol a di-dor. 2) Defnyddiwch dull lluosi byr i ddatrys: i. 237 x 7 ii. 634 x 6 3) Defnyddiwch dull rhannu hir i ddatrys: i. 767 ÷ 27 ii. 986 ÷ 36 2
AMCANION RHANNU • Sut mae rhannu yn cael ei addysgu yn CA 2. • I ail-ymgyfarwyddo gyda dulliau ysgrifennedig • I fod yn ymwybodol or camsyniadau a sydd gen rhai disgyblion o rannu 3
O Dan pa amgylchiadau mae rhannu yn briodol? Mae yna dri strwythyr ble mae rhannu yn amlygu ei hyn. Y ddau strwythyr yma yw: • Strwythyr rhannu cyfartal; • Gwrthidro i Lluosi • Strwythyr Cymhareb. Dysgu ac Addysgu Nid ‘Rhannu rhwng’ yw’r unig fodel o rannu. Rhannu yn gyfartal yw un strwythyr. Dylid dim rhoi gormod o bwysa ar y cysyniad a iaith i rannu gan anghofio am dan rhannu fod yn 4 Gwrth-wyneb i lluosi
Beth yw’r strwythyr rhannu cyfartal? Mae’r Strwythyr Rhannu Cyfartal yma yn cyfeirio at sefyllfa ble maint yn cael ei rannu yn gyfartal I rhif briodol ac yna rydym yn ceisio darganfod faint sydd ty mewn i pob rhan. e. e. 20 marble yn cael ei rannu’n gyfartal rhwng 4 plentyn mewn gêm. Dysgu ac Addysgu Y termau a geiriau allweddol yma yw; ‘rhannu’n gyfartal’ ag ‘faint ym mhob rhan’. 5
Strwythyr gwrthdro i lluosi Gwrthdro I Lluosi yn dehongli yn wahanol. Nawr y cwestiwn yw: ‘Faint o grwpiau o 4 sydd yn y set o 20? ? ’ Rhannu 20 yn hafal I 4 grwp, faint sydd ym mhob grwp? Nawr yn rhannu 20 i bedwar grwp, faint o grwpiau? 6
Strwythyr cymhareb Pan rydym yn cymharu dau rhif; drwy ysgrifennu cymhareb 20: 80 Dysgu ac Addysgu 7 .
CYNNYDD MEWN RHANNU 3 4 5 6
Bydd y camau a sydd yn datblygu tuag at rhannu hir yn cwmpasu blynyddoedd 4 -6 drwu ddechrau ag: ØBl 4 - DU ÷ U ØBL 5 - CDU ÷ U ØBL 6 - CDU ÷ TU
Dechrau adio Ymarferol, cyfri gwrthrychau a gwneud cysylltiadau gyda cyplysu grwpiau o wrthrychau.
Dechrau defnyddio llinell rhif Defnyddio cychwyn – neidio – a cofnodi. (a) 2 adio 3 = 5 0 1 2 3 4 5 6 7 8 9 10
Dulliau adio pen Er mwyn adio yn llwyddiannus rhaid: • Galw i gof ffeithiau allweddol (bondiau rhif hyd at 10, 20 & 100, dwblu a. y. y. b) a cymhwyso hyn i gyfrifiadau. • Adnabod fod all adio mewn unrhyw drefn a defnyddio hyn i adio cyfuniadau gwahanol. DDd + DDd • Dosrannu DDd mewn ffurf gwahanol ac bod yn fentrus a creadigol. • Deall y iaith a sydd yn gysylltiedig ac adio sef: mwy nag, swm, plws, cyfanswm, cyfanrhif, i gyd at ei gilydd a. y. y. b
Dulliau ysgrifennedig o adio CAM 1: Llinell rhif gwag Mae’r linell rhif gwag yn help i gofnodi pan yn anelu tuag at rhif. Mae’r camau yn aml yn pontio ac yn pasio lluosrifau o ddeg 8 + 7 = 15 48 + 36 = 84 neu:
Drosodd i chi! Defnyddiwch linell rhif i ddarganfod. 53 + 24 86 + 17 149 + 38
Dulliau ysgrifennedig o adio CAM 2: Dosrannu Y cam nesaf yw i gofnodi dosrannu rhifau. Mae dosrannu degau ac unedau yn adlewyrchu y dull colofn yn yr ystyr maent yn cael eu paru unedau gydag unedau a. y. y. b Mae hyn hefyd yn ddull pen. e. e: 47 + 76 = 47 + 70 + 6 = 117 + 6 = 123 neu 47 + 76 = 40 + 7 + 6 = 110 + 13 = 123 Mae rhifau wedi ei dosrannu yna yn cael ei Ysgrifennu uwchben ei gilydd i gysylltu a dull colofn.
Drosodd i chi! Defnyddiwch dosrannu i ddarganfod: 65 + 38 71 + 26 94 + 45
Dulliau ysgrifennedig o adio CAM 3: Dull colofn ehangach Gall ddisgyblion yn awr symyd yn eu blaenau gan dosrannu yn eu penau ac ysgrifennu dull colofn. Dylie disgyblion gychwyn gan adio yr unedau. NODER: Mae adio y degau 47 + 76 yma yn gyfesur ag 40 + 70 = 110 yn hytrach nag 4 + 7 = 11.
Drosodd i chi! Defnyddiwch y dull colofn ehangach i ddatrys: 65 + 38 123 + 59 315 + 172
Dulliau ysgrifennedig o adio CAM 4: Dull Colofn Yn y dull llawn yma, mae cofnodi wedi ei leihau. Cofnodir rhifau a sydd yn cario o dan y linell, drwy gyfeirio at ‘cario 10’ a ‘cario 100’ yn hytrach nag cario 1. Yna maent yn datblygu i Tri. Dd + DDd a Tri. Dd + Tri. Dd ac yna ddegolion.
Tynnu
BETH YW’R GWAHANOL CYD-DESTYNAU MAE TYNNU YN CAEL EI DDEFNYDDIO? MAE YNA LLAWER O GYD DESTYNAU BLE RHAID I NI ADNABOD MAI TYNNU YW’R DULL BRIODOL. Mae’r rhain wedi ei dosbarthu i 4 grwp: • Strwythur Dosrannu • Strwythur Lleihau • Strwythur Cymharu • Strwythur Gwrth-wyneb i Adio 21
What are the different kinds of situation to which the operation subtraction applies? Mae’n bwysig fod athrawon yn adnabod ac yn rhoi cyfle i ddisgyblion arbrofi a phob un or strwythurau, yn hytrach nag dim ond gofyn 56 – 10. . e. e, I ddarganfod faint yn fwy mae geneth sydd yn 167 cm yn fwy na hogyn sy’n 159 cm (Strwythur Cymharu), gellir disgybl adnabod fod angen gwneud ‘ 167 − 159’, ond wedyn dehongli hyn gan feddwl ‘Faint sydd rhaid adio i 159 er mwyn cael 167? ’ (Strwythur Gwrth-wyneb i Adio). 22
Dysgu ac Addysgu Mae ymgyfarwyddo gyda’r amrediad yma o strwythurau yn mynd i alluogi disgyblion i ddehongli cyfrifiad tynnu mewn sawl ffurf ac o ganlyniad cefnogi ei gallu i ymdrin a ystod eang o gyfrifiadau a cyddestynau. 23
Beth yw y Strwythurau Tynnu? Strwythur Lleihau Strwythur Dosrannu Yn y strwythur dosrannu Bu maint yn cael ei dosrannu, ac mae rhaid tynnu i ddarganfod faint sydd ar ol. Pan fydd maint wedi ei leihau ac mae’n rhaid darganfod beth yw gwerth sydd ar ol. Strwythur Cymharu Pan mae dau rhif yn cael ei gymharu ac mae’n gwneud synnwyr i dynnu er mwyn cymharu y ddau rhif. e. e. Os yw pris beic yn £ 149 ac mae’n cael ei leihau gan £ 25, beth yw’r pris newydd? e. e. Mae 17 marbl mewn bocs, mae 5 yn cael ei Tynnu allan; faint sydd ar ol? Strwythur Gwrth-wyneb i Adio Lle bum yn ceisio darganfod faint rydym angen adio ar ben rhif er mwyn cyrraedd targed o riw fath. Mae’n tanlinellu y ffaith for y gwrth-wyneb i tynnu yw adio. e. e. Gan fod 28+52 = 80, felly maen gwneud synnwyr fod 80 -52 yn gwneud 52. 24
Beth yw y Strwythurau Tynnu? Strwythur Dosrannu Strwythur Lleihau Strwythur Cymharu Strwythur Gwrth-wyneb i Adio Pan yr ydym yn gosod ddau Pan rydym yn cychwyn o rhif Lle bynag rydym yn dechrau Pan fydd cost yn cael ei ac yn gofyn faint dwi angen i gyda rhif, ac yna mae yna leihau, neu fesur tymheredd rif wrth ei gilydd ac yn dymuno ei cymharu. gyrraedd y targed rhif yn cael ei dynnu oddi- yn cael ei leihau. wrtho. Pres Mesur Pres Gwrthrychau Mabolgampau Tymheredd Pres Siop Gwaith Mesur 25
FFOCWS YMCHWIL: ADIO A THYNNU Greer (1997), Reviewing research into children’s responses to word problems in mathematics, identifies a widespread tendency for children to disregard the reality of the situations described by the text of the problem. His analysis suggests that an explanation is not to be found in some cognitive deficit of the children, but rather in the culture of the classroom where word problems are presented in a stereotyped fashion. Children learn that the solution involves the application of one of the basic arithmetical operations to the numbers mentioned in the text and look for clues as to which operation they should use. 26
Cyflwyno Tynnu Dechrau gyda enghreifftiau ymarferol sy’n dilyn i ‘tynnu’. ‘ Defnyddio gwrthrychau lluniau numicon, blociau canaeuon. (1, 2, 3 mam yn dal y pry, 6 crocodeil yn nofio yn yr afon. . )
Dulliau Pen o Tynnu • Er mwyn tynnu yn effeithiol rhaid : • Galw i gof ffeithiau tynnu yn sydyn (bondiau rhif 10, 20 & 100, haneri a. y. y. b) a chymhwyso’r rhain mewn cyfrifiadau. • Tynnu rhifau un digid a dau ddigid yn y pen • Deall fod tynnu yn gwrth-wyneb i adio, ac fod y drefn mewn tynnu yn holl bwysig. (dechrau gyda’r rhif mwyaf) • Deall y iaith o tynnu sef: llai, minws, tynnu, gwahaniaeth a. y. y. b
PROBLEM GYDA TYNNU Cwestiynau cyffredin • Mae Sam wedi cynilo 57 c. Mae ei chwaer wedi casglu 83 c Faint yn fwy sydd gan Sam nag ei chwaer? Mae Samir yn rhedeg 50 m mewn ras tatw. Mae’n tynnu’n ol ar ol 18 m Faint yn fwy sydd ganddo ei fynd? • Mae Nisha a Charlie yn pwyso ffrwythau. Mae Nisha’s gyda 38 g. Mae gan Charlies 50 g. Faint yn drymach yw ffrwythau Charlies nag rhai Nisha? • Mae blodyn haul yn 38 cm o uchder. Mae un arall yn 83 cm. Beth yw’r gwahaniaeth mewn uchder rhwng y ddau flodyn?
Written methods for Subtraction CAM 1: LLINELL RHIF Mae’r dull yma yn helpu wrth gyfrif i fynnu: • Cyfri i fynnu- gall camau gael ei cofnodi wrth gyfri i fynnu oddi wrth y rhif lleiaf tuag at y rhif mwyaf. neu
Dull ysgrifenedig o Tynnu CAM 1: LLINELL RHIF Gyda ymarfer dylie disgyblion gofnodi llai a phenderfynnu i gyfri yn ol neu ymlaen. Mae’n hanfodol fod trafodaeth pam bryd ac beth yw’r gorau yn y sefyllfa… Gyda rhif tri digid gall cofnodi gael ei leihau ond mae angen gallu cyfrifo 178 + ? = 200 ag 200 + ? = 326 yn y pen. neu
Drosodd i chi! Pryd y bysech yn defnyddio llinell rhif? 1) 59 - 11 2) 86 – 68 3) 142 – 35 4) 92 -9
Dull ysgrifenedig o Tynnu CAM 2: Dull Colofn Ehangach Gall ei cymwyso ar gyfer rhifau tri digid. Esiampl: 741 - 367
Dull ysgrifenedig o Tynnu CAM 3: Dull Colofn Ehangach Mae’r dull yma yn pontio ynesaf gyda’e dull flaenorol, ac yn gallu bod yn feuchys.
Drosodd i chi! Defnyddiwch y dull colofn ehangach i ddarganfod. 73 - 39 123 - 58 315 - 177
Dull ysgrifenedig i Tynnu CAM 4: Dull Colofn Mae’r dull ehangach yn cael ei fireinio i:
Drosodd i chi! Defnyddiwch y dull colofn i ddarganfod y canlynol. 83 - 58 166 - 47 402 - 175
SYNIADAU GWERSI
SYNIADAU GWERSI
Be ydan ni wedi addysgu? Sut? Pa effaith y caiff ar dysgu ac addysgu?
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SAFONAU http: //wales. gov. uk/docs/dcells/publications/090915 becomingateacheren. pdf S 1. 1 S 1. 2 S 1. 3 S 1. 4 S 1. 5 S 1. 6 S 1. 7 S 1. 8 S 2. 1 Deall anghenion dysgu pawb, gwneud y gorau o botensial a dangos ymrwymiad Ystyried y dysgwyr a pharch at ei gilydd Ysbrydoli dysgwyr Cyfathrebu â rhieni a gofalwyr Hybu’r ysgol fel rhan o’r gymuned ehangach Gweithio gydag eraill Ymrwymiad i ddatblygiad proffesiynol Gweithio o fewn y gyfraith S 2. 2 S 2. 3 S 2. 4 S 2. 5 S 2. 6 S 2. 7 Gwybodaeth am bynciau (a) Y Cyfnod Sylfaen (b) Cyfnod Allweddol 2 Nodau a chanllawiau’r Cwricwlwm Cenedlaethol Cynnydd rhwng cyfnodau Sut y mae datblygiad yn effeithio ar ddysgu Defnyddio technoleg gwybodaeth a chyfathrebu (TGCh) Anghenion Addysgol Arbennig (AAA) Hybu ymddygiad da S 3. 1. 1 S 3. 1. 2 S 3. 1. 3 S 3. 1. 4 S 3. 1. 5 Gosod amcanion Cynllunio gwersi Defnyddio adnoddau Gweithio mewn timoedd Dysgu y tu allan i’r ysgol S 3. 2. 1 S 3. 2. 2 S 3. 2. 3 S 3. 2. 4 S 3. 2. 5 S 3. 2. 6 S 3. 2. 7 Strategaethau asesu Asesu i gefnogi dysgu Asesu o fewn gofynion cenedlaethol Diwallu anghenion y dysgwyr Cymraeg neu Saesneg fel iaith ychwanegol Cofnodi cynnydd Adrodd i rieni ac i eraill S 3. 3. 1 Disgwyliadau uchel S 3. 3. 2 [Addysgu sgôp / ystod oed arbenigol] S 3. 3. 3 Rhoi gwersi effeithiol S 3. 3. 4 Gwahaniaethu wrth addysgu S 3. 3. 5 Cymorth i ddysgu Cymraeg neu Saesneg fel iaith ychwanegol S 3. 3. 6 Ystyried amrywiaeth S 3. 3. 7 Rheoli amser S 3. 3. 8 Defnyddio adnoddau’n ddiogel ac yn effeithiol S 3. 3. 9 Rheoli ymddygiad S 3. 3. 10 Defnyddio TGCh S 3. 3. 11 Hyd a lled y profiad addysgu S 3. 3. 12 Rhoi gwaith cartref S 3. 3. 13 Gweithio gydag eraill S 3. 3. 14 Cyfle cyfartal S 3. 3. 15 Datblygu cynaliadwy a dinasyddiaeth fyd-eang
Addition and Subtraction CA 2/KS 2 English S 2. 1 S 2. 2 S 2. 4
PREVIOUS LECTURES STARTER 1) Describe the difference between discrete and continuous data. 2) Use the short multiplication method to find: i. 237 x 7 ii. 634 x 6 iii. Use long division to find: iv. 767 ÷ 27 v. 986 ÷ 36 44
AIMS § To have an overview of the skills children need to calculate. § To understand how to support your child with maths. § To be more aware of the models, images and resources used to support the teaching and learning of maths. § Think about the progression from mental towards written methods.
ADDITION
What are the different kinds of situation to which the operation of division applies? There are two basic categories of real-life problems that are modeled by the mathematical operation we call addition. The problems in each of these categories may vary in terms of their content and context, but essentially they all have the same structure. • The Aggregation structure • The Augmentation structure I find it is useful in teaching to have these in mind to ensure that children have opportunities to experience the full range of situations and, most importantly, the associated language that they have to learn to connect with addition. 47
What is the aggregation structure of addition? I use the term aggregation to refer to a situation in which two (or more) quantities are combined into a single quantity and the operation of addition is used to determine the total. For example: There are 15 marbles in one circle and 17 in another: how many marbles altogether? Teaching and Learning The key language to be developed in the aggregation structure of addition includes: How many altogether? How much altogether? The total? The sum of. 48
What is the augmentation structure of addition? I use the term augmentation to refer to a situation where a quantity is increased by some amount and the operation of addition is required in order to find the augmented or increased value. For example, the price of a bicycle costing £ 149 is increased by £ 25: what is the new price? Teaching and Learning It should just be mentioned at this stage that if the number added were a negative number, then the addition would not result in an increase, but in a decrease. The key language to be developed in the augmentation structure of addition includes: Start at and count on, increase by, go up by. Start on notches and then count! 49
What are some of the contexts in which children will meet addition in the aggregation and augmentation structures? AGGREGATION Problems involved with money and measurement, wherever a summative answer is needed. A concept of summing quantities together. AUGMENTATION Problems involved with money and temperature, specifically when money is increased or decreased. Children’s age is a good example. Augmentation is a concept that connects with the use of number lines. 50
PROGRESSION OF ADDITION METHODS
Beginning to add Practical, counting objects and relating addition to combining two groups of objects
Beginning to use a number track Use of the number track- hopping and recording. (a) 2 and 3 makes 5 0 1 2 3 4 5 6 7 8 9 10
Mental Strategies for Addition • Secure mental addition requires the ability to: • Recall key number facts instantly (number pairs to 10, 20 & 100, doubles etc) and to apply these to similar calculations • Recognise that addition can be done in any order and use this to add mentally different combinations of one and two digit numbers • Partition two-digit numbers in different ways, including adding the tens and units separately before recombining • Understand the language of addition including more than, sum, plus, greater than, total, altogether etc)
Written methods for Addition Stage 1: The empty number line helps to record the steps on the way to calculating the total. The steps often bridge through a multiple of 10. 8 + 7 = 15 48 + 36 = 84 or:
Over to you! Use a number line to find answers to these sums. 53 + 24 86 + 17 149 + 38
Written methods for Addition Stage 2: Partitioning The next stage is to record mental methods using partitioning. Partitioning both numbers into tens and ones mirrors the column method where ones are placed under ones and tens under tens. This also links to mental methods. eg: 47 + 76 = 47 + 70 + 6 = 117 + 6 = 123 or 47 + 76 = 40 + 7 + 6 = 110 + 13 = 123 Partitioned numbers are then written under one another:
Over to you! Use Partitioning to find answers to these sums. 65 + 38 71 + 26 294 + 145
Written methods for Addition Stage 3: Expanded method in columns Children can now move on to a layout showing the addition of the tens to the tens and the ones to the ones separately. Children should start by adding the ones digits first. The addition of the tens in the calculation 47 + 76 is described as 40 + 70 = 110 as opposed to 4 + 7 = 11.
Over to you! Use the expanded column method to find answers to these sums. 65 + 38 123 + 59 315 + 172
Written methods for Addition Stage 4: Column method In this method, recording is reduced further. Carry digits are recorded below the line, using the words 'carry 10' or 'carry 100', not 'carry 1'. Later, extend to adding three two-digit numbers, two three-digit numbers, numbers with different numbers of digits and decimals.
SUBTRACTION
What are the different kinds of situation to which the operation subtraction applies? There is a daunting range of situations in which we have to learn to recognize that the appropriate operation is subtraction. I find it helpful to categorize these into at least the following four categories: • The Partitioning structure; • The Reduction structure; • The Comparison structure; and • The Inverse-of-addition structure. 63
What are the different kinds of situation to which the operation subtraction applies? Each of these has its own characteristic language patterns, all of which have to be connected in the learner’s mind with subtraction. It is important for teachers to be aware of this range of structures, to ensure that children get the opportunity to learn to apply their number skills to all of them. Being able to connect subtraction with the whole range of these situations and to switch freely from one to the other is also the basis for being successful and efficient at mental and informal strategies for doing subtraction calculations. For example, to find out how much taller a girl of 167 cm is than a boy of 159 cm (which is the comparison structure), a child may recognize that this requires the subtraction ‘ 167 − 159’, but then do the actual calculation by interpreting it as ‘what must be added to 159 to get 167? ’ (which is the inverse of addition). 64
Teaching and Learning Familiarity with the range of subtraction structures and the associated language patterns will enable children to interpret a subtraction calculation in a number of ways and hence increase their ability to handle these calculations by a range of methods. 65
What are the structures of subtraction? Partitioning Structure Reduction Structure Comparison Structure Inverse–of-Addition Structure The partitioning structure The reduction structure is The comparison structure The inverse-of-addition structure refers to situations refers to a situation in which similar to ‘take away’ but it is refers to a completely different set of situations, where we have to determine a quantity is partitioned off in associated with different what must be added to a language. It is simply the namely, those where some way or other and reverse process of the subtraction is required to given quantity in order to subtraction is required to make a comparison between reach some target. The calculate how many or how augmentation structure of phrase ‘inverse of addition’ addition. It refers to a two quantities. much remains. underlines the idea that situation in which a quantity subtraction and addition are For example, there are 17 is reduced by some amount inverse processes. and the operation of marbles in the box, 5 are subtraction is required to find removed, how many are For example, that since the reduced value. left? 28 + 52 comes to 80, then 80 − 52 must be 28. The For example: if the price of subtraction of 52 undoes the a bicycle costing £ 149 is effect of adding 52. reduced by £ 25, what is the new price? 66
What are the most common contexts associated with the structures of subtraction? Partitioning Structure Reduction Structure Realistic examples of the First, this structure is encountered whenever we reduction structure mainly start with a given number of occur in the context of things in a set and a subset money. The key idea which signals is taken away (removed, the operation of subtraction destroyed, eaten, killed, blown up, lost or whatever). is that of ‘reducing’, for example, reducing prices and costs, cutting wages Money and shopping. For example, we might plan and salaries. to spend £ 72 from our savings of £ 240 and need to For example, if a person’s work out how much would council tax of £ 625 is cut by be left (that is, carry out the £ 59, the reduced tax is determined by the subtraction, 240 − 72). subtraction, 625 − 59. Measurment Comparison Structure Inverse–of-Addition Structure There are many commonplace situations where we encounter this structure: for example, any situation where we have a number of objects or a The first step in this is to decide which is the larger number of individuals and we and which is the smaller and require some more in order to to articulate this using the reach a target. appropriate language. The most convincing The process of comparison examples for many will be in the context of sport. is a central idea in all measurement contexts Wherever two numbers occur we will often find ourselves wanting to compare them. 67
RESEARCH FOCUS: SUBTRACTION Greer (1997), Reviewing research into children’s responses to word problems in mathematics, identifies a widespread tendency for children to disregard the reality of the situations described by the text of the problem. His analysis suggests that an explanation is not to be found in some cognitive deficit of the children, but rather in the culture of the classroom where word problems are presented in a stereotyped fashion. Children learn that the solution involves the application of one of the basic arithmetical operations to the numbers mentioned in the text and look for clues as to which operation they should use. 68
Introducing ‘take away’ Begins with practical demonstrations of subtraction relating to ‘take away’. Use of number tracks, pictures and songs (10 green bottles, 5 little speckled frogs).
Beginning to take away • Number tracks leading to number lines introduced for recording ‘jumps’ back. • 8 - 3=5 1 2 3 4 5 6 7 8
Mental Strategies for Subtraction • Secure mental subtraction requires the ability to: • Recall key subtraction facts instantly (inverse of number pairs to 10, 20 & 100, halves etc) and to apply these to similar calculations • Mentally subtract combinations of one and two digit numbers • Understand that subtraction is the inverse of addition and recognise that subtraction can’t be done in any order (it has to start with the larger number) • Understand the language of subtraction including less, minus, take away, difference between etc)
The problem with subtraction Typical Questions • Sam has saved 57 p. Her sister has saved 83 p How much more money does Sam have than his sister? • Samir is running a 50 metre potato race. He drops out after 18 metres How much further does he have to go? • Nisha and Charlie weigh fruit. Nisha’s weighs 38 g. Charlies weighs 50 g. How much heavier is Charlies fruit than Nishas? • One sunflower is now 38 cm high. Another is 83 cm high. What is the difference between the heights of the sunflowers?
Written methods for Subtraction Stage 1: The empty number line helps to record the steps in mental subtraction. • Counting Up - the steps can also be recorded by counting up from the smaller number to find the difference or
Written methods for Subtraction Stage 1: The empty number line With practice, children will need to record less information and decide whether to count back or forward. It is useful to ask children whether counting up or back is the more efficient for calculations such as 57 - 12, 86 - 77 or 43 - 28. With three-digit numbers the number of steps can again be reduced, provided that children are able to work out answers to calculations such as 178 + ? = 200 and 200 + ? = 326 mentally. or
Over to you! When would you use a number line? 1) 59 - 11 2) 86 – 68 3) 142 – 35 4) 92 -9
Written methods for Subtraction Stage 2: Expanded column method It can also be applied to three and four digit numbers. Example: 741 - 367
Written methods for Subtraction Stage 3: Expanded column method Depending on the numbers it can get quite complicated and this stage may need a lot of time and perseverance!
Over to you! Use the expanded column method to find answers to these sums. 73 - 39 123 - 58 315 - 177
Written methods for Subtraction Stage 4: Column method The expanded method is eventually reduced to:
Over to you! Use the compact column method to find answers to these sums. 83 - 58 166 - 47 402 - 175
LESSON IDEAS
LESSON IDEAS
What have we learnt? How? What effect will this have on learning?
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STANDARDS http: //wales. gov. uk/docs/dcells/publications/090915 becomingateacheren. pdf S 1. 1 S 1. 2 S 1. 3 S 1. 4 S 1. 5 S 1. 6 S 1. 7 S 1. 8 S 2. 1 Understanding everyone’s learning needs, maximizing potential and demonstrating commitment Consideration for learners and mutual respect Inspiring learners Communication with parents and careers Promoting the school in the wider community Working with others Commitment to professional development Working within the law S 2. 2 S 2. 3 S 2. 4 S 2. 5 S 2. 6 S 2. 7 Subject knowledge (a) Foundation Phase (d) Key Stage 2 National Curriculum aims and guidelines Progression between stages How development affects learning Using information and communications technology (ICT) Special Educational Needs (SEN) Promoting good behaviour S 3. 1. 1 S 3. 1. 2 S 3. 1. 3 S 3. 1. 4 S 3. 1. 5 Setting objectives Planning lessons Using resources Working in teams Out-of-school learning S 3. 2. 1 S 3. 2. 2 S 3. 2. 3 S 3. 2. 4 S 3. 2. 5 S 3. 2. 6 S 3. 2. 7 Assessment strategies Assessment to support learning Assessment against national requirements Meeting learners’ needs English or Welsh as an additional language Recording progress Reporting to parents and others S 3. 3. 1 High expectations S 3. 3. 2 [Teaching specialist scope / age range] S 3. 3. 3 Delivering effective lessons S 3. 3. 4 Differentiating teaching S 3. 3. 5 Supporting English or Welsh as an additional language S 3. 3. 6 Taking account of diversity S 3. 3. 7 Time management S 3. 3. 8 Using resources safely and effectively S 3. 3. 9 Managing behaviour S 3. 3. 10 Using ICT S 3. 3. 11 Length and breadth of teaching experience S 3. 3. 12 Providing homework S 3. 3. 13 Working with others S 3. 3. 14 Equal opportunities S 3. 3. 15 Sustainable development and global citizenship
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