Virginia Birch MFNERC Numeracy Specialist

Mental Math Strategies Grade 1 to 4 Virginia Birch MFNERC Numeracy Specialist

Overview • Mental Math… what is it? • Grade 1 to 3 Strategies • Indicators from the Provincial Report Card

Mental Math… what is it • Conceptual strategies that enhance flexible thinking and number sense and number skills (critical numeracy) • calculating mentally without the use of external memory aids. • provides a cornerstone for all estimation processes offering a variety of alternate algorithms and non-standard techniques for finding answers K - Gr 8 Manitoba Curriculum Framework of Outcomes 2013 K - Gr 8 Manitoba Curriculum Framework of Outcomes 2013

Mental Math… what is it • developing mental math skills and recalling math facts automatically • Facts become automatic for students through repeated exposure and practice. • When facts are automatic, students are no longer using strategies to retrieve them from memory. K - Gr 8 Manitoba Curriculum Framework of Outcomes 2013

Mental Math… what is it • One of the Math Competencies for the Grade 3 and Grade 7 Math Assessment • (see report templates)

Mental Math: • Should not be timed. Students differ on the amount of time they need to process concepts. • Can be done daily approximately five minutes for a daily math routine. • Can be practiced with math games or learning centers where students can practice the strategies. • Create a Mental Math Bulletin Board • Create an Estimation Bulletin Board

The development of mental math strategies is greatly enhanced by sharing and discussion. Students should be given the freedom to adapt, combine, and invent their own strategies.

Math Tools you can use… • Ten Frames • Base 10 Blocks • 100 – Chart • Number Line • Array Cards • Dominoes • Finger Patterns • Linking cubes Going from concrete to pictorial to abstract…

Counting On – Grade 1 Concept: Addition Meaning: Students begin with a number and count on to get the sum. Students should begin to recognize that beginning with the larger of the two addends is generally most efficient. Example: for 3 + 5 think5 + 1 + 1 + 1 is 8; think 5, 6, 7, 8

Practising the strategy… 2+7= 9+3= 3+12=

Counting Back – Grade 1 Concept: Subtraction Meaning:Students begin with the minuend and count back to find the difference. Example: for 6 – 2 think 6 – 1 – 1 is 4; think 6, 5, 4

Practising the Strategy 9-2= 10-3= 7-1=

Using One More – Gr 1, 2 Concept: Addition Meaning:Starting from a known fact and adding one more. Example: for8 + 5 if you know8 + 4 is 12 and one more is 13

Practising the Strategy 5+6= 6+7= 8+9=

Using One Less - Gr 1, 2 Concept: Addition Meaning:Starting from a known fact and taking one away. Example: for 8 + 6 if you know 8 + 7 is 15 and one less is 14

Practising the strategy 7+6= 9+8= 6+5=

Making 10 – Gr 1, 2 Concept: Addition, Subtraction Meaning: Students use combinations that add up to ten and can extend this to multiples of ten in later grades. Example: 4 + ____ is 10 7 + ____ is 10; so 23 + ____ is 30

Practising the strategy 28 +___ = 30 15 +___=20 16 + ___= 40

Starting from Known Doubles – Gr 1 Concept: Addition, Subtraction Meaning: Students need to work to know their doubles facts. Example: 2 + 2 is 4 and4 – 2 is 2

Practising the strategy 3+3=__ , so ___-3=___ 9+9=__ , so ___-9=___ 8+8=__ , so ___-8=___

Using Addition to Subtract – Gr 1, 2, 3 Concept: Subtraction Meaning: This is a form of part-part-whole representation. Thinking of addition as: part + part = whole Thinking of subtraction as: whole – part = part Example:for12 – 5 think 5 + ____ = 12 so12 – 5 is 7

Practising the Strategy 13-7= ? , think 7 +___= 13 11-6= ? , think 6 +___=11 15-7= ? , think 7+___= 15

The Zero Property of Addition – Gr 2 Concept: Addition, Subtraction Meaning: Knowing that adding 0 to an addend does not change its value, and taking 0 from a minuend does not change the value. Example: 0 + 5 = 5; 11 – 0 = 11

Using Doubles – Gr 2, 3 Concept: Addition, Subtraction Meaning: Students learn doubles, and use this to extend facts: using doubles doubles plus one (or two) doubles minus one (or two) Example: for 5 + 7 think 6 + 6 is 12; for 5 + 7 think 5 + 5 + 2 is 12 for 5 + 7 think 7 + 7 – 2 is 12

Practising the strategy for6+ 8,think doubles for 6+ 8, think double 6 plus two for 6 + 8, think double 8 minus two

Building on Known Doubles – Gr 2, 3 Concept: Addition, Subtraction Meaning:Students learn doubles, and use this to extend facts. Example: for7 + 8 think 7 + 7 is 14 so 7 + 8 is 14 + 1 is 15

Adding from Left to Right – Gr 3 Concept: Addition Meaning: Using place value understanding to add 2-digit numerals. Example:for25 + 33 think 20 + 30 and 5 + 3 is 50 + 8 or 58

Making 10 – Gr 3 Concept: Addition, Subtraction Meaning: Students use combinations that add up to ten to calculate other math facts and can extend this to multiples of ten in later grades. Example:for8 + 5 think8 + 2 + 3 is 10 + 3 or 13

Compensation – Gr 3 Concept: Addition, Subtraction Meaning: Using other known math facts and compensating. For example, adding 2 to an addend and taking 2 away from the sum. Example: for 25 + 33 think 25 + 35 – 2 is 60 – 2 or 58

Commutative Property – Gr 3 Concept: Addition Meaning: Switching the order of the two numbers being added will not affect the sum. Example: 4 + 3 is the same as 3 + 4

Compatible Numbers – Gr 3, 4 Concept: Addition, Subtraction Meaning: Compatible numbers are friendly numbers (often associated with compatible numbers to 5 or 10). Example:for 4 + 3 students may think 4 + 1 is 5 and 2 more makes 7

Array – Gr 3 Concept: Multiplication, Division Meaning: Using an ordered arrangement to show multiplication or division (similar to area). Example:for 3x4 think    for 12÷3think   

Practising the strategy 5x5= 3x4= 4x2=

Commutative Property – Gr 3 Concept: Multiplication Meaning: Switching the order or the two numbers being multiplied will not affect the product. Example: 4 x 5 is the same as 5 x 4

Skip Counting – Gr 3 Concept: Multiplication Meaning: Using the concept of multiplication as a series of equal grouping to determine a product. Example: for4 x 2 think 2, 4, 6, 8 so 4 x 2 is 8

Practising the Strategy 2x5= 3x4= 5x4=

Zero Property of Multiplication– Gr 4 Concept:Multiplication Meaning: Multiplying a factor by zero will always result in zero. Example: 30 x 0 is 0 0 x 15 is 0

Multiplicative Identity– Gr 4 Concept: Multiplication Meaning: Multiplying a factor by one will not change its value. Dividing a dividend by one will not change its value. Example: 1 x 12 is12 21 ÷ 1 is 21

Skip-Counting from a Known Fact– Gr 4, 5 Concept: Multiplication, Division Meaning:Similar to the counting on strategy for addition. Using a known fact and skip counting forward or backward to determine the answer. Example:for3 x 8 think3 x 5 is 15 and skip count by threes15, 18, 21, 24

Practising the Strategy 4 x 7 = 6 x 8= 8 x 7= 9 x 8=

Doubling or Halving– Gr 4, 5 Concept: Multiplication, Division Meaning:Using known facts and doubling or halving them to determine the answer. Example:for 7 x 4, think the double of 7 x 2 is 28 for 48 ÷ 6, think the double of 24 ÷ 6 is 8

Practising the Strategy 8 x 4 = think double 8 x 2 = ___ 32 ÷ 4 = think double 16 ÷ 4 = ____

Using the Pattern for 9s- Gr 4 Concept: Multiplication, Division Meaning:Knowing the first digit of the answer is one less than the non-nine factor and the sum of the product’s digits is nine. Example:for7 x 9 think one less than 7 is 6 and 6 plus 3 is nine, so 7 x 9 is 63

Practising the Strategy 4 x 9 = 36 5 x 9 = 45 6 x 9 = 54 7 x 9 = 63 8 x 9 = 72

Repeated Doubling– Gr 4, 5 Concept: Multiplication Meaning:Continually doubling to get to an answer. Example:for3 x 8, think3 x 2 is 6, 6 x 2 is 12, 12 x 2 is 24

Virginia Birch MFNERC Numeracy Specialist