Content Area: Math
Unit Title: Subtraction of 2-Digit Numbers with & w/out Regrouping Unit: 7
Target Course/Grade Level: 2 Timeline: 4 weeks
Unit Summary: Students will learn to regroup so they can accurately subtract two digit numerals.
Primary interdisciplinary connections: Language Arts
NJ Standard 9.1: 21 st – Century Life & Career Skills
Standard 9.1: All students will demonstrate the creative, critical thinking, collaboration, and problemsolving skills needed to function successfully as both global citizens and workers in diverse ethnic and organizational cultures.
Strand: A. Critical Thinking and Problem Solving
C. Collaboration, Teamwork and Leadership
Content Statement:
9.1.4.A.5: The ability to recognize a problem and apply critical thinking and problem-solving
skills to solve the problem is a lifelong skill that develops over time.
9.1.4.C.1: Practice collaborative skills in groups, and explain how these skills assist in
completing tasks in different settings such as home, play or school.
21 st century themes and skills: Critical Thinking and Problem Solving, Collaboration, Teamwork and
Leadership
Mathematical Practices:
2.MP.1. Make sense of problems and persevere in solving them.
2.MP.2. Reason abstractly and quantitatively.
2.MP.3. Construct viable arguments and critique the reasoning of others.
2.MP.4. Model with mathematics.
2.MP.5. Use appropriate tools strategically.
2.MP.6. Attend to precision.
2.MP.7. Look for and make use of structure.
2.MP.8. Look for and express regularity in repeated reasoning.
Learning Targets
Domain: Numbers & Operations in Base Ten 2.NBT
Measurement and Data 2.MD
Operations and Algebraic Thinking 2.OA
Cluster:
Use place value understanding and properties of operations to add and subtract.
Work with time and money.
Represent and interpret data.
Standard # Standards
2.NBT.5 Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.

2.NBT.7
2.NBT.8
Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.
Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.
2.NBT.9
2.MD.8
2.MD.10
2.OA.1
Explain why addition and subtraction strategies work, using place value and the properties of operations.
Solve word problems involving dollar bills, quarters, dimes, nickels, and pennies, using $ and ¢ symbols appropriately. Example: If you have 2 dimes and 3 pennies, how many cents do you have?
Draw a picture graph and a bar graph (with single-unit scale) to represent a data set with up to four categories. Solve simple put-together, take-apart, and compare problems using information presented in a bar graph.
Use addition and subtraction within 100 to solve one- and two-step word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.
Cumulative Progress Indicator (CPI)
Apply critical thinking and problem-solving skills in classroom and family settings.
CPI#
9.1.4.A.5
9.1.4.C.1 Practice collaborative skills in groups, and explain how these skills assist in completing tasks in different settings (at home, in school, and during play).
Unit Essential Questions

How can I use what I know about number relationships to add and subtract?

Why is recognizing what strategy to use for a specific purpose, helpful?
Unit Enduring Understandings

Different strategies (mental, paper, drawing) can be used to subtract numbers fluently.

Different strategies (mental, paper, drawing, concrete models) can be applied to subtract within 100.

Place value affects the other place values when subtracting. (regrouping, trading, composing/decomposing)

When subtracting two or three digit numbers, knowing the value of that digit, in a given position, determines the next step one must take to solve an equation.

Multiples of 10 and 100 can be used as landmark numbers in computation.

Words or drawings can be used to explain subtraction strategies.

Money knowledge can be used to solve word problems.


Picture & Bar graphs charts and tables can be used to solve comparative and subtraction problems.
Unit Learning Targets
Students will ...

Use manipulatives to show regrouping of tens and ones.

Explain how regrouping is done and represent with manipulatives.

Compute subtraction problems of 2 digit numbers (w/&w/o regrouping).

Subtract a 1 digit from a 2 digit and record in vertical format.

Subtract amounts of money less than a dollar with and without regrouping.

Solve problems involving subtraction using data from a table.

Solve a problem by using estimation to determine reasonableness of difference.

Use clue words to prompt solving word problems for double digit subtraction.

Use addition to check subtraction .

Estimate differences by rounding to the nearest 10.

Identify and solve problems with too much information.
Evidence of Learning
Summative Assessment

Illustrate/explain subtracting two-digit numbers with/without regrouping.

Accurately compute two two-digit numbers with/without regrouping for subtraction.

Accurately subtract money amounts less than $1.00 with/without regrouping.

Give a table with various two-digit numbers and solve subtraction with/without regrouping.

Choose from a list of strategies/tools one could use to solve a given two-digit math subtraction equation to determine which is the best way to attain the correct answer.

Give an equation using 2 two-digit numbers. Solve the problem giving an estimate and exact difference.

Identify clue word (highlight, circle or underline) that indicates subtraction for a word problem and write the equation with correct answer.
Equipment needed: place value cubes, multiple decks of cards, dice, and spinners
Teacher Instructional Resources:
Everyday Math
Math Their Way
Scott Foresman Mathematics Program: Chapter 6
Formative Assessments
Observe students as they ….
 work with manipulatives
 complete work sheets/workbooks
 play games, complete activities

Integration of Technology:
SMARTBoard to play online games and utilize on line resources.
ELMO to use for demonstration purposes.
Utilize resources from Scott Foresman by using Login in: https://www.pearsonsuccessnet.com/snpapp/login/login.jsp
Technology Resources:
Click the links below to acc http://www.free-training-tutorial.com/math-games/subtraction-math-basketball.html?1& Student figures out the difference of two digit number and scores basketball points. http://www.coolmath4kids.com/subtraction/number-monster-subtraction-basics.htm
Student figures out the difference of two digit number and computer tells if answer is correct while giving a percentage of correct answers. http://www.oswego.org/ocsd-web/games/Ghostblasters3/ghostsub3.html
Student is given a subtraction problem and a set of ghosts with numbers on them. Student aims target at correct answer and is given points if correct. It is a timed game.
Opportunities for Differentiation:
Decelerate: Continue using place value blocks and/or beans for longer time so the concept of regrouping is clearly understood. Use the Scott Foresman online tools to give another visual aide for learning the concept.
Accelerate: Give Students problems using three digit subtraction. Give multi-step word problems using subtraction with regrouping.
Teacher Notes: Even though students have learned to regroup for addition, do not assume this regrouping will come easily. Subtraction is a harder concept and with regrouping it will take multiple times using the proper manipulatives. Practice, Practice, Practice.