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Number Sense, Grades K-2: Training Day 3,
Subtraction

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Session 3:  Subtraction – Designing purposeful instruction to move students beyond direct modeling and counting, and to think more algebraically

Doing and un-doing are key ideas in mathematics. We’ll explore having students be as comfortable with subtraction as with addition and understanding the relationships between the two operations. Seeing subtraction as both “difference” and “take away” helps students have a more robust understanding of subtraction. Open number lines will be explored as an instructional strategy that is helpful in problem solving. We will continue to focus on how to encourage your students to adopt more sophisticated strategies and ways to record their thinking.

Standards Addressed

View the Frameworks for the Minnesota Mathematics & Science Standards at: http://www.scimathmn.org/stemtc/

NUMBER & OPERATIONS

Primary Focus
Use objects and pictures to represent situations involving combining and separating.
K.1.2.1 Use objects and draw pictures to find the sums and differences of numbers between 0 and 10.
K.1.2.2 Compose and decompose numbers up to 10 with objects and pictures.

Primary Focus
1.1.2 Use a variety of models and strategies to solve addition and subtraction problems in real-world and mathematical contexts.
1.1.2.1 Use words, pictures, objects, length-based models (connecting cubes), numerals and number lines to model and solve addition and subtraction problems in part-part-total, adding to, taking away from and comparing situations.
1.1.2.2 Compose and decompose numbers up to 12 with an emphasis on making ten.
1.1.2.3 Recognize the relationship between counting and addition and subtraction . . .

 

 


Teacher Materials

Standards.doc
100 Number Chart-0.pdf
Classroom Conversation.pdf
Subtraction Participant Handout.pdf
Classroom Conversation 2.doc
Classroom Conversation 2.pdf
Interview Focus on Subtraction.docx
Interview Focus on Subtraction.pdf
Number Sense K-2 PPT Merged.pdf

 

 

Primary Focus
Demonstrate mastery of addition and subtraction basic facts; add and subtract one- and two-digit numbers in real-world and mathematical problems.
2.1.2.1 Use strategies to generate addition and subtraction facts including making tens, fact families, doubles plus or minus one, counting on, counting back, and the commutative and associative properties. Use the relationship between addition and subtraction to generate basic facts.
2.1.2.2 Demonstrate fluency with basic addition facts and related subtraction facts.
2.1.2.3 Estimate sums and differences up to 100.
2.1.2.4 Use mental strategies and algorithms based on knowledge of place value and equality to add and subtract two-digit numbers. Strategies may include decomposition, expanded notation, and partial sums and differences.
2.1.2.5 Solve real-world and mathematical addition and subtraction problems involving whole numbers with up to 2 digits.

Work on the primary focus standards and benchmarks will continue to help develop the following:
Understand the relationship between quantities and whole numbers up to 31.
K.1.1.2 Read, write, and represent whole numbers from 0 to at least 31. Representations may include numerals, pictures, real objects and picture graphs, spoken words, and manipulatives such as connecting cubes.
K.1.1.3 Count with and without objects, forward and backward to at least 20.
K.1.1.4 Find a number that is 1 more or 1 less than a given number.
K.1.1.5 Compare and order whole numbers, with and without objects, from 0 to 20.

Work on the primary focus standards and benchmarks will continue to help develop the following:
Count, compare and represent whole numbers up to 120, with an emphasis on groups of tens and ones.
1.1.1.1 Use place value to describe whole numbers between 10 and 100 in terms of tens and ones.
1.1.1.2 Read, write and represent whole numbers up to 120. Representations may include numerals, addition and subtraction, pictures, tally marks, number lines and manipulatives, such as bundles of sticks and base 10 blocks.
1.1.1.5 Compare and order whole numbers up to 120
1.1.1.6 Use words to describe the relative size of numbers.

Work on the primary focus standards and benchmarks will continue to help develop the following:
Compare and represent whole numbers up to 1000 with an emphasis on place value and equality.
2.1.1.1 Read, write and represent whole numbers up to 1000. Representations may include numerals, addition, subtraction, multiplication, words, pictures, tally marks, number lines and manipulatives, such as bundles of sticks and base 10 blocks.
2.1.1.2  Use place value to describe whole numbers between 10 and 1000 in terms of hundreds, tens and ones. Know that 100 is 10 tens, and 1000 is 10 hundreds.
2.1.1.5  Compare and order whole numbers up to 1000.

ALGEBRA

Primary Focus
Use number sentences involving addition and subtraction basic facts to represent and solve real-world and mathematical problems; create real-world situations corresponding to number sentences.
1.2.2.1 Represent real-world situations involving addition and subtraction basic facts, using objects and number sentences.
1.2.2.2 Determine if equations involving addition and subtraction are true.
1.2.2.3 Use number sense and models of addition and subtraction, such as objects and number lines, to identify the missing number in an equation such as:  2 + 4 = ""; 3 + "" = 7;
5 = ¨ – 3.
1.2.2.4 Use addition or subtraction basic facts to represent a given problem situation using a number sentence.

Primary Focus
Use number sentences involving addition, subtraction and unknowns to represent and solve real-world and mathematical problems; create real-world situations corresponding to number sentences.
2.2.2.1 Understand how to interpret number sentences involving addition, subtraction and unknowns represented by letters. Use objects and number lines and create real-world situations to represent number sentences.
2.2.2.2 Use number sentences involving addition, subtraction, and unknowns to represent given problem situations. Use number sense and properties of addition and subtraction to find values for the unknowns that make the number sentences true.

Work on the primary focus standards and benchmarks will continue to help develop the following:
Recognize, create, describe, and use patterns and rules to solve real-world and mathematical problems.
2.2.1.1 Identify, create and describe simple number patterns involving repeated addition or subtraction, skip counting and arrays of objects such as counters or tiles. Use patterns to solve problems in various contexts.

 


The Region 11 Math And Science Teacher Partnership (MSTP) 2014-2015 project
is funded through Title II, Part B of ESEA, as amended by the NCLB Act of 2001.


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