Teaching algorithms
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Teaching Algorithms. How algorithms are taught Valerie Sereno. Simple Addition and Subtraction. Addition in Early Stage 1 and Stage 1 (K-2) are mostly taught horizontally: 3 + 4= 7 they do not move into vertical algorithms until late in year 2.

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Teaching Algorithms

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Teaching algorithms

Teaching Algorithms

How algorithms are taught

Valerie Sereno


Simple addition and subtraction

Simple Addition and Subtraction.

  • Addition in Early Stage 1 and Stage 1 (K-2) are mostly taught horizontally: 3 + 4= 7 they do not move into vertical algorithms until late in year 2.

  • In early stage 1 (K) all are taught using diagrams or objects that the students can see and physically manipulate.

  • Students need to know number facts i.e;knowing numbers before and after, counting backwards and forwards and skip counting.

  • Students learn to use the bigger number and count on.


Addition and subtraction algorithm strategies

Addition and Subtraction algorithm strategies.

  • Using doubles and near doubles; 7 + 8 = becomes 7 + 7 + 1= 15.

  • Using combination s of 10 i.e 4 +6 and 7 +3 and bridging to 10 breaking down algorithms i. e 17+5, 17+3= 20 then 20+2=22 .

  • Using related addition and subtraction factsie 8+7=15 and 15-7=8

  • These cannot be applied unless the student has a thorough grasp of basic number facts.


Trading

TRADING

  • The process of trading in addition and subtraction has changed and is taught as a vertical algorithm.

  • i. e T U T U

    4 5 + 3 7 _

    1 7 1 9

    We no longer “borrow and pay back” we “trade”

    H T U H T U

    7 6 5 + 7 6 5 _

    3 9 3 9


Multiplication

Multiplication

  • Students MUST have a strong knowledge of number facts to understand and solve multiplication problems. Memorising the times tables means students can solve more difficult multiplication problems with much more ease.

  • Multiplication does not get taught thoroughly until stage 2 (year 3)

  • So 3 x 4 is basically 3+3+3+3 (or 4+4+4) (repeated addition)

  • Mixed multiplication

    T U T U

    1 6 x 3 6 x

    9 2 3


Division

DIVISION

  • To put it simply, it is “sharing”

  • Division is taught more thoroughly again in stage 2.

  • Is much easier if the student understands multiplication- as they can be seen as “related” 4 x 3 = 12 as 12 ÷ 4 = 3It can also be verbalised as how many times does 4 go into 12. Can also be seen as repeated subtraction.

  • Division can be the most confusing of all processes but the best way for students who are struggling is to draw a diagram.


Division1

DIVISION

  • It becomes difficult when dealing with “remainders” or “leftovers”- this is taught more thoroughly in stage 3 (yr 5-6)

    r

  • 4 68 4 67

    r

    12 144 12 149

    As you can see these are solved due to knowledge of multiplication.

  • Long Division can be taught but is no longer a mandatory part of the NSW mathematics curriculum in primary schools.


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