Transcript File - Ballycarrickmaddy Primary School

MENTAL
ARITHMETIC
TO BE EFFECTIVE MENTAL
ARITHMETIC SHOULD:
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Provide regular short sessions of 10 minutes each day.
This is more valuable than infrequent lengthy ones.
Provide a variety of activities each week.
Instruct, demonstrate, explain and illustrate ideas and
skills.
Put the emphasis on discussion and on sharing the
different strategies that children use to find answers.
Make connections with previous learning.
Use correct terms and teach new vocabulary.
Target individuals, or small groups, with particular
questions.
Make sure sessions are non-threatening and pupils feel
comfortable in each one.
STRANDS of MENTAL
MATHEMATICS
Mental Strategies - MS
Teaching the most commonly used
strategies for performing
mental calculations. However, pupils
may develop their other, equally valid,
strategies.
EXAMPLES - MS
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Counting on or back in ones e.g. 14 + 3
(LEVEL 1),
10s e.g. 30 + 20 30 → 40 → 50, (LEVEL 2)
2s, 5s and 100s (Level 3)
When adding count on in simple unitary
fractions (LEVEL 4)
¼
¼ ¼
e.g. 2 ½ + ¾ 2 ½ → 2 ¾ → 3 → 3 ¼
EXAMPLES - MS
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When subtracting, count back in tenths (LEVEL 4)
0.1
0.1
0.1
e.g. 7.8 – 0.3 7.8 → 7.7 → 7.6 → 7.5
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When adding or subtracting, count on or back in a combination
of ones, tens, hundreds and thousands, tenths and hundredths
(LEVEL 5)
40
200
1000
e.g. 7000 – 5760 5760 → 5800 → 6000 → 7000
EXAMPLES - MS
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Rearranging numbers to make calculations easier
e.g. 2+ 13 is the same as 13 + 2 (large amount
first) (LEVEL 2)
Rounding and adjusting: 83 – 35 = 48
Looking for multiples of 10: 27 14 13 56
Near Doubles
Understanding the Number System
(UNS)
Skills in mental mathematics should be
developed in parallel with a sound
understanding of our number system.
This strand outlines the development
of a sense of number and the
interrelationship within number.
EXAMPLES - UNS
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Count orally, in ones, forwards and then
backwards. Count individually, in groups and as
a class (LEVEL 1)
Count on and back in ones, twos, tens, fives
from a given number (Level 2)
Counting orally forwards and backwards in
halves and quarters (LEVEL 3)
Counting orally forwards and backwards in
tenths between whole numbers and crossing
over whole numbers (level 4)
Using combinations (level 5)
EXPLORING PATTERNS – multiplication
patterns / counting patterns
EXAMPLES - UNS
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Recognising and writing numbers (word and
number format)
Understanding the position of numbers on a
number line (before / after)
Understand and use the effect of multiplying
whole numbers by 10 and 100
Recognising numbers that can be divided by 10
and 100
Ordering Numbers – increasing / decreasing
Appreciating the inverse relationship between
operations : ADDITION and SUBTRACTION
/ MULTIPLICATION and DIVISION
Approximation and Estimation (AE)
The skills of approximating and
estimating are important in the
application of mathematics to real-life
situations. This strand is closely
related to
‘Understanding the Number System’.
EXAMPLES - AE
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Having a feel for the size of a set of objects
Approximating numbers to the nearest 10, 100,
1000
Estimating calculations as a means of checking
Quick Recall (QR)
The quick recall of number facts is
essential for efficient mental
calculations.
EXAMPLES - QR
 Knowing
doubles
 Addition and subtraction within
20
 Multiplication / Division Facts
 Measures
 Shape and Space
Mental Calculations (MC)
This strand presents calculations which
pupils might be expected to carry out
mentally as their skills develop.
EXAMPLES - MC
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Building number fact families within 5 / 10 (level 1)
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Adding / subtracting
1, 2 or 0 from any number (level 1)
Find what must be added to a number to make 10 and then 20
(level 2)
e.g. 6 and how many make 10
13 and how many make 20
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Find what must be added to any two-digit number to make the
next higher multiple of 10
e.g. 26 and how many more make 30
EXAMPLES - MC
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Adding and subtracting single digit numbers to and from 2 digit
numbers bridging the ten
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Add or subtract 100 or multiples of 100 to or from any 3-digit
number
e.g. 300 + 100
760 – 200
342 + 400
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Add or subtract any two 2-digit numbers within 100, bridging
the 10 (LEVEL 4)
e.g. 25 + 17 then bridging the 100 78 + 42
Find the difference between pairs of 2 or 3-digit numbers which
are close (Level 4)
e.g. 484 – 475
ACTIVITY
WALT – identify the characteristics associated with the
different strands within Mental Arithmetic
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Top Tips:
Listen to the views and opinions of others when
making your choices
Reach agreement through negotiation and compromise
Select, classify, compare and evaluate information
Look closely at the vocabulary