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Making Math Matter: Adding & Subtracting Decimals

  Classroom Resource Information  

Title:

Making Math Matter: Adding & Subtracting Decimals

URL:

https://aptv.pbslearningmedia.org/resource/85277c3a-dcfa-4254-aea1-91811b9d22f7/adding-and-subtracting-decimals/

Content Source:

PBS
Type: Audio/Video

Overview:

In this video, teachers will learn classroom strategies for teaching decimal addition and subtraction in this professional development video from Making Math Matter.

Content Standard(s):
Mathematics
MA2019 (2019)
Grade: 5
3. Using models and quantitative reasoning, explain that in a multi-digit number, including decimals, a digit in any place represents ten times what it represents in the place to its right and 1/10 of what it represents in the place to its left.

a. Explain patterns in the number of zeros of the product when multiplying a number by powers of 10, using whole-number exponents to denote powers of 10.

b. Explain patterns in the placement of the decimal point when a decimal is multiplied or divided by a power of 10, using whole-number exponents to denote powers of 10.
Unpacked Content
Evidence Of Student Attainment:
Students:
  • Use models to illustrate the relationship between two successive place values in whole numbers and decimals.
  • Explain that a digit in one place represents 1/10 of what it represents to its left or the place value is 10 times the place value on the right.
  • Use strategies to find products and explain patterns when multiplying by powers of 10.
    Example: The product of 420 x 200 = 42 x 10 x 2 x 100 is the same as (42 x 2) x (10 x 100) = 84 x 1000 = 84,000 shows multiplying by three powers of 10 shifts the digits in the product three place values greater (to the left.)
  • Use strategies to find products and quotients and use place value understanding to explain patterns in the placement of the decimal point when involving a power of 10.
  • Write powers of 10 in standard form and using exponential notation.
Teacher Vocabulary:
  • Digit
  • Decimal
  • Decimal point
  • Thousandths
  • Hundredths
  • Tenths
  • Base-ten
  • Expanded form
  • Place value
  • Power of 10
  • Factor
  • Base
  • Exponent
  • Product
Knowledge:
Students know:
  • Each place value position represents 10 times what it represents in the place to its right.
    Example: In 433, the underlined 3 represents 3 tens and has a value of 30 which is ten times the value of the 3 ones to its right.
  • Place value understanding is extended to apply reasoning that a place value position represents 1/10 of what it represents in the place value to its left.
    Example: In 433, the underlined 3 represents 3 ones and has a value of 3 which is one-tenth of the value of the 3 tens or 30 to its left.
  • A given number multiplied by a power of 10 shifts the digits in the given number one place value greater (to the left) for each factor of 10. -A given number divided by a power of 10 shifts the digits in the given number one-tenth of the value (to the right) for each factor of 10.
Skills:
Students are able to:
  • Reason and explain the relationship between two successive place values.
  • Explain patterns of zeros of the product when multiplying by powers of 10.
  • Explain patterns in placement of decimals when multiplying or dividing by power of 10.
  • Write powers of 10 using exponential notation.
Understanding:
Students understand that:
  • The relationship of adjacent places values in the base ten system extend beyond whole numbers to decimal values.
  • Multiplying or dividing by a power of 10 shifts the digits in a whole number or decimal that many places to the left or right respectively.
Diverse Learning Needs:
Essential Skills:
Learning Objectives:
M.5.3.1: Use place value understanding to round whole numbers to the nearest 10 or 100.
M.5.3.2: Compare two three-digit numbers based on meanings of the hundreds, tens, and ones digits using >, =, and < symbols to record the results of comparisons.
M.5.3.3: Identify that the three digits of a three-digit number represent amounts of hundreds, tens, and ones.

Prior Knowledge Skills:
  • Reason and explain the relationship between two successive place values.
  • Explain patterns of zeros of the product when multiplying by powers of 10.
  • Explain patterns in placement of decimals when multiplying or dividing by power of 10.
  • Write powers of 10 using exponential notation.

Alabama Alternate Achievement Standards
AAS Standard:
M.AAS.5.3 Compare base-10 models up to 99 and whole numbers up to 100 to determine symbols (<, >, =).


Mathematics
MA2019 (2019)
Grade: 5
4. Read, write, and compare decimals to thousandths.

a. Read and write decimals to thousandths using base-ten numerals, number names, and expanded form.

Example: 347.392 = 3 × 100 + 4 × 10 + 7 × 1 + 3 × (1/10) + 9 × (1/100) + 2 × (1/1000).

b. Compare two decimals to thousandths based on the meaning of the digits in each place, using >, =, and < to record the results of comparisons.
Unpacked Content
Evidence Of Student Attainment:
Students:
  • Given a decimal number in one form (words, base-ten numerals, expanded), identify the number in another form.
  • Read decimals with number names.

  • Example: Read 4.023 as "four and 23 thousandths."
  • Write decimals using base-ten numerals and expanded form.

  • Example: 4.023 as 4 x 1 + 2 x 1/100 + 3 x 1/1000 or 4 x 1 + 2 x 0.01 + 3 x 0.001.
  • Use place value understanding to compare two decimals.
Teacher Vocabulary:
  • Compare
  • Decimal
  • Thousandths
  • Hundredths
  • Tenths
  • Symbol
  • Greater than
  • Less than
  • Equal
  • Place value strategy
  • Expanded form
  • Expanded notation
Knowledge:
Students know:
  • How to read and write whole numbers in standard form, word form, and expanded form.
  • How to compare two whole numbers using place value understanding.
  • Prior place value understanding with whole numbers is extended and applied to decimal values.
  • Recognize and model decimal place value using visual representations to compare.
Skills:
Students are able to:
  • Read and write decimal values in word form, standard form, and expanded form.
  • Compare decimals to thousandths using <, >, or = .
Understanding:
Students understand that:
  • the adjacent place value relationship in the base ten system extends to decimals and is used to write decimals in expanded form and compare decimals.
Diverse Learning Needs:
Essential Skills:
Learning Objectives:
M.5.4.1: Recognize decimals as parts of a whole.
M.5.4.2: Compare whole numbers.
M.5.4.3: Write whole numbers in words and expanded form.
M.5.4.4: Read whole numbers.
M.5.4.5: Define expanded notation and standard form.
M.5.4.6: Convert a number written in expanded to standard form.
M.5.4.7: Define hundredths and thousandths.
M.5.4.8: Compare two three-digit numbers based on meanings of the hundreds, tens, and ones digits using >, =, and < symbols to record the results of comparisons.
M.5.4.9: Identify comparison symbols.
Examples: >, =, and <.

Prior Knowledge Skills:
  • Read and write decimal values in word form, standard form, and expanded form.
  • Compare decimals to thousandths using <, >, or = .
  • Understand rounding decimals using place value.

Alabama Alternate Achievement Standards
AAS Standard:
M.AAS.5.3 Compare base-10 models up to 99 and whole numbers up to 100 to determine symbols (<, >, =).


Mathematics
MA2019 (2019)
Grade: 5
8. Add, subtract, multiply, and divide decimals to hundredths using strategies based on place value, properties of operations, and/or the relationships between addition/subtraction and multiplication/division; relate the strategy to a written method, and explain the reasoning used.

a. Use concrete models and drawings to solve problems with decimals to hundredths.

b. Solve problems in a real-world context with decimals to hundredths.
Unpacked Content
Evidence Of Student Attainment:
Students:
  • Use strategies based on place value, properties of operations, and relationship between addition and subtraction to find sums and differences of decimals.
  • Use strategies based on place value, properties of operations, and relationship between multiplication and division to find products and quotients of decimals.
  • Use models to justify the sum, difference, product or quotient of decimals.
  • Solve real-world problems with decimals to hundredths.
Note: Products are limited to thousandths and quotients are either whole numbers or decimals terminating at the tenths or hundredths place.
Teacher Vocabulary:
  • Decimal
  • Tenths
  • Hundredths
  • Place value
Knowledge:
Students know:
  • Strategies based on place value understanding, properties, and relationship between operations to find the sum, difference, product, and quotient of whole numbers.
  • How to write decimal notation for fractions with denominators of 10 or 100.
  • Use estimation strategies to assess reasonableness of answers.
Skills:
Students are able to:
  • Use concrete models, drawings, and strategies to add, subtract, multiply, and divide decimals.
  • Relate strategies for operations with decimals to a written method and explain reasoning used.
  • Solve real-world context problems involving decimals.
Understanding:
Students understand that:
Problems involving operations with decimals
  • Can be solved using a variety of strategies based on place value, properties of operations, or the relationship between the operations.
  • Can be illustrated using concrete models or drawings.
Diverse Learning Needs:
Essential Skills:
Learning Objectives:
M.5.8.1: Use decimal notation for fractions with denominators 10 or 100.
M.5.8.2: Multiply and divide within 100, using strategies such as the relationship between multiplication and division or properties of operations.
M.5.8.3: Add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.
M.5.8.4: Apply properties of operations as strategies to multiply and divide.
M.5.8.5: Identify that 100 can be thought of as a bundle of ten tens, called a "hundred".
M.5.8.6: Identify that the numbers 100, 200, 300, 400, 500, 600, 700, 800, 900 refer to one, two, three, four, five, six, seven, eight, or nine hundreds (and 0 tens and 0 ones).
M.5.8.7: Recall basic addition, subtraction, multiplication, and division facts.

Prior Knowledge Skills:
  • Use fraction equivalence to add and subtract fractions and mixed numbers with unlike denominators.
  • Find whole number quotients and remainders using a variety of strategies based on place value and properties of operations.
  • Illustrate and explain the calculation using equations, arrays, and area models.
  • Use concrete models, drawings, and strategies to add, subtract, multiply, and divide decimals.
  • Relate strategies for operations with decimals to a written method and explain reasoning used.
  • Solve real-world context problems involving decimals.

Alabama Alternate Achievement Standards
AAS Standard:
M.AAS.5.8 Add decimals to tenths using concrete models, drawings, and manipulatives without regrouping.


Tags: addition, decimal, place value, professional development, subtraction
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  This resource provided by:  
Author: Stephanie Carver
Alabama State Department of Education