Kyrene School District

Grade 2 Revised 5/10/16

Grade 2 Focus Unit 3: Adding and Subtracting within 100 / Suggested Duration: 5 weeks
In this focus unit, students build on the strategies they used in Grade 1 to begin to refining their addition strategies and develop strategies for subtraction within 100. These concepts are introduced at the beginning of the year because addition and subtraction is a major focus of Grade 2; therefore, students need time to practice to reach fluency by the end of the year.
Stage 1 Desired Results
Enduring Understandings / Essential Questions
STANDARDS ASSESSED IN THIS UNIT
Major content standards listed in BOLD, Supporting content standards in italics
2.OA.A.1 / 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. (See Table 1.)
2.OA.B.2 / Fluently add and subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.
2.OA.C.3 / Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counting them by 2s; write an equation to express an even number as a sum of two equal addends.
2.NBT.A.2 / Count within 1000; skip-count by 5s, 10s, and 100s.
2.NBT.B.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.B.6 / Add up to four two-digit numbers using strategies based on place value and properties of operations.
2.NBT.B.8 / 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.B.9 / Explain why addition and subtraction strategies work, using place value and the properties of operations. (Explanations may be supported by drawings or objects.)
2.MD.B.6 / Represent whole numbers as lengths from 0 on a number line diagram with equally spaced points corresponding to the numbers 0, 1, 2,…, and represent whole-number sums and differences within 100 on a number line diagram.
Embedded Standards
2.MD.C.7 / Tell and write time from analog and digital clocks to the nearest five minutes, using a.m. and p.m.
2.MD.C.8 / 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?
Stage 3: Plan for Learning
Principal Resources & Routines
Principal Resource
IDS 2 - Unit 3 (Including Common Core Lesson 2.5A)
Routines
2.MD.B.6, 2.MD.C.7, 2.MD.C.8
Incorporate these routines in addition to IDS Classroom Routines: Fosnot’s Mini-lessons for Extending Addition and Subtraction; 2.NBT.A.2 - Counting by 5's, 10's and 25's (link to money); Tell time to the nearest quarter hour; Number Sense Routines, CGI word problems
Notes
-Fluency Expectations for 2nd grade are addition and subtraction to 20 (mental strategies 2.OA.2) and addition and subtraction to 100 (2.NBT.B.5).
Mental strategies help students make sense of number relationships as they are adding and subtracting within 20. The ability to calculate mentally with efficiency is very important for all students.
Mental strategies may include the following:
  • Counting On/Counting Back
  • Making Tens (9 + 7 = 10 + 6)
  • Decomposing a number leading to a ten ( 14 – 6 = 14 – 4 – 2 = 10 – 2 = 8)
  • Fact Families (8 + 5 = 13 is the same as 13 - 8 = 5)
  • Doubles
  • Near Doubles- DoublesPlus One (7 + 8 = 7 + 7 + 1), Doubles Minus One (7 + 6 = 7 + 7 – 1)
/ Academic Vocabulary
  • Add tens and ones
  • Addend – any number used to get the sum or total
  • Bundle – to put individual units together to make a larger unit, for example, connecting 10 individual linking cubes to make a ten
  • Compose – put a number together using other numbers
  • Decompose – separate a number into parts using other numbers
  • Equal – the same as in value or size
  • Equation a mathematical sentence in which one part is the same as, or equal to, the other part
  • Even number– number that can make 2 equal groups, even numbers end with 2, 4, 6, 8, or 0
  • Hundred – a group or bundle of 10 tens or 100 ones
  • Odd number – number that cannot make 2 equal groups, odd numbers end with 1, 3, 5, 7, or 9
  • Place value – the value of a digit is determined by its place in a number; ones place, tens place
  • Tally marks – marks used to record counting
  • Ten – a group or bundle of 10 ones
  • Total/sum – the result when two or more numbers are added together
  • Thousand – a group or bundle of 10 hundreds, 100 tens, or 1,000 ones

Meeting the Needs of All Students
Resources for Enrichment and Intervention
Additional Resources
-Teaching Student-Centered Mathematics K-3, Ch. 6
p. 165 (6.1) Ten-Frame Adding and Subtracting
-Developing Number Concepts, Book 2
p. 151 (3-28) Related Combinations: Tall Stacks
p. 157 (3-30) Working with Ten-Shapes
p. 168 (3-34) Two Ten-Shapes: Addition and Subtraction
-Developing Number Concepts, Book 3
p. 109 (1-45) Addition and Subtraction of Two-Digit Numbers
p. 116 (1-46) Story Problems
Grade 2 Resources for Enrichment and Intervention- 2.OA.B.2, 2.OA.C.3 / Possible Universal Design for Learning for This Unit
  • UDL Guidelines 2.0 with links to examples
  • UDL Learning Wheel– scroll through the interactive tool to find examples for providing UDL supports

Multiple Means of Representation (WHAT)
Recognition--the ways information is presented
Multiple Means of Action and Expression (HOW)
Strategic--participation or demonstration of knowledge and skills
Provide options for...
Multiple Means of Engagement (WHY)
Affective--How students are engaged and motivated

Note: If you find a link is broken or not working, please contact your math coach or the Curriculum & Learning Services Department.