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Maths Workshop for Parents. Handy hints on terminology and calculation methods. Intro Theory Methods for multiplication and division Place value multiplication and division Order of Operations Factors and Multiples Prime Factorisation. Do it your way!. 25x19 5% of 86 248-99 103-98
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Maths Workshop for Parents Handy hints on terminology and calculation methods
Intro • Theory • Methods for multiplication and division • Place value multiplication and division • Order of Operations • Factors and Multiples • Prime Factorisation
Do it your way! • 25x19 • 5% of 86 • 248-99 • 103-98 • ½ of 378 • 1+2+3+4+5+6+7+8+9+10+11=
Mentally add and subtract anypair of 2-digit numbers • For most children during the latter part of year 3 • Children will be using a variety of mental methods by this time
Mental first • 56+ 29 or 56 +29 • Children cease to “say” the numbers, seeing only digits in columns e.g. “6 add 9” instead of “56 add 29”
2000 -102 This is most sensibly done by counting back, not by decomposition
25x8 or 25 x 8 • Children relying on written procedures forget how much they can do mentally. 25x8 is double 25x4
The calculating repertoire “Brain paper”: • Mental recall of number facts • Mental methods of calculation Real paper (and use of calculators) • Jottings to record mental calculations • Informal written methods • Standard written methods
Expanded Written Methods Standard Written Methods Calculator Mental Calculations with jottings Informal Methods Mental Recall The calculating continuum
The calculating repertoire • Children constantly move up and down the continuum • Learning a new method of calculating does not mean other ways are no longer relevant • Children should always be looking for calculations they can do wholly or partly mentally
A structured approach to calculation An approach based on the skills of mental calculation: • Remembering number facts • Using known facts to derive new ones • Familiarity with the number system and relationships between numbers • Having a repertoire of mental calculation strategies • Understanding of the four operations and how they are related
Addition and subtraction • Partitioning is an important strategy children must learn • A number line is a method of informal calculation that works for any size of number, for both operations. • Knowing 33+ 25 = 58 leads to the following: 25+ 33 = 58, 58-33 = 25, 58-25 = 33 25+ ? = 58 ?+? = ?+?
Multiplication and division • Multiplication is repeated addition, division is repeated subtraction • Doubling, halving, partitioning, and multiplying by 10, 100, 1000 are essential mental strategies • 3x4=12 leads to 4x3, 12÷3, 12÷4, 6x4, etc, 30x4, 300x4, 120÷4 etc • Children need to see facts as arrays
Moving from informal to formal methods • At every stage, teachers first use examples that children can easily do mentally • Children then see how the steps in a written procedure link to what they do in their heads • They then move to using numbers that cannot easily be dealt with mentally, including money and decimal numbers • Partitioning and place value are crucial concepts and estimation of size of answers is essential.
Long multiplication • Grid method • Compact / formal / column method
Long division • Chunking • Bring down remainders (DMSBR)
Place value multiplication and division • Move digits one column to the left to x10 • Move digits one column to the right to ÷10 • Essential skill • Measure conversions • Percentages
Order of operations (BIDMAS) B = brackets I = indices D = division or M = multiplication A = addition or S = subtraction 32 + 4 x (7 – 2) = 32 + 4 x 5 = 9+ 4 x 5 = 9+ 20 = 29
Factors and multiples • You multiply two or more numbers together to find their product. • The product of 2 and 7 is 14: 2 x 7 = 14 • 14 is a multiple of 2 and is also a multiple of 7 • Any whole number can be written as the product of two factors.
Factors and multiples • You can list all the factor pairs of a number or • You can write the factors in a list • If there are only two factors, the number is a prime number • A square number has an odd number of factors
HCF and LCM • Highest Common Factor • Lowest Common Multiple
Prime Numbers and Prime Factorisation • Important to learn divisibility rules • Try to recognise primes up to 100
Open Forum • Any specific queries? • Future workshops?