2 Related Courses
 5012030: Mathematics  Grade One (Specifically in versions: 2014 and beyond (current))
 7712020: Access Mathematics Grade 1 (Specifically in versions: 2014 and beyond (current))
3 Access Points

Access Point
 MAFS.1.OA.1.AP.1a: Use base ten blocks to model simple addition or subtraction equations within 20 based upon a word problem.
 MAFS.1.OA.1.AP.1b: Solve addition and subtraction word problems within 20.
 MAFS.1.OA.1.AP.1c: Solve onestep addition and subtraction word problems where the change or result is unknown (4 + _ = 7) or (4 + 3 = __), within 20 using objects, drawings or pictures.

Lesson Plan

Math Place Value: The students will use ten frames to show place value of two digit numbers 0100. Students will use different manipulatives to show place value of two digit numbers. The students will be able to recognize the correct place value for a two digit numbers. 
Out of Sight Missing Addends: Students will learn how to use manipulatives to solve missing addends in math problems. 
Subtraction Race: OBJECTIVE: Through a game promoting physical activity, students will practice subtracting numbers with a difference between 1 and 10. 
A Family of Facts: In this handson lesson plan, students use the analogy of a literal family (including cutouts of boys, girls, and houses) to learn about fact families and the inverse nature of addition and subtraction. 
Bunny Addition: This lesson integrates language arts, music, and math. The children will listen to the story Count on Bunnies. They will be given the opportunity to act out the story and solve bunny equations. After listening to the song "Five Young Rabbits," the children will take turns being rabbits and pantomiming the actions as the class sings. The children will combine the rabbits at the end of each verse to see how many rabbits have been added. Then they will work in pairs to create their own rabbit equations.

An Apple of Day: This is a handson lesson which uses apples to introduce the concept of "half" and to teach simple addition. 
Supermarket Sweep Day 2: Students will participate in a supermarket game and follow a shopping list. Students will compare the quantity of items "purchased" and graph results. Students will also learn a song about shopping in a supermarket. 
Links Away: Hopping Backwards on the Number Line: This lesson uses the number line model to teach students how to generate differences. First, the teacher will demonstrate this by having students hop to subtract numbers on a physical number line (such as carpet squares or a shower curtain marked appropriately). Students will also investigate whether the commutative property holds for subtraction.

Cookie Subtraction: In this lesson, the teacher shares the book, "Mmm... Cookie Simple Subtraction". The students follow along by representing the problems in the book with cookie manipulatives and recording the equations for each problem. The lesson incorporates a variety of subtraction problem types. 
Addition Stories at the Food Store: In this lesson, students will solve addition whole number word problems (within 20) with realworld scenarios by using manipulatives or drawings and equations. 
Flower Power Flower Company MEA & STEAM* Activity: This STEAM (Science, Technology, Engineering, Art, and Math) lesson has been designed around a ModelEliciting Activity.
This Model Eliciting Activity (MEA) is written at a 1st grade level. The Flower Power MEA provides students with an real world problem in which they must work as a team to design a plan to select the best flower arrangement for a special event. The resource was primarily designed as an MEA so the time and teacher instructions are primarily based on the MEA. The additional activities will take several hours of instruction but include watching and discussing a video about the parts of plants, reading a book, and discussing the art in the book as well as additional art by the book author/illustrator.

Solving Word Problems Using Story Structure: In this lesson, students will learn how to use their knowledge of beginning, middle, and end to solve word problems that include result unknown, change unknown, and start unknown. They will learn how to use a modified story map to write an equation to represent the problem. 
Word Problem Lesson: In this lesson, students will be able to solve compare word problems. 
Making 11: In this lesson students use manipulatives to discover how to build the number 11. This lesson is great for novice teachers or for teachers who have changed to 1st grade. 
Quilt Squares: Students will use pattern blocks to create a quilt square for the Quick Quilters Society. They will have to consider information on a data chart to help them create their squares. They will have to add up the cost to make their square, too. 
Fill It Up  Piñatas!: This is an MEA lesson that focuses on students' problem solving skills. After reading a story about what is in a piñata, students are asked to help a company find the best way to fill a piñata. It focuses on math skills, including counting and recognizing numbers to 120.

An Amazing Sunny Day Story: In this lesson, students are shown a picture of a beach scene. They are asked to identify groups of things within the picture. There are three predetermined groups of ten with noticeable parts (people, starfish, coconuts). Using the picture, students will identify a group of ten, create an addition equation for the parts, and transfer the equation into sentences to tell the story. 
Pete's Groovy Button Problems: This lesson uses a familiar character, Pete the Cat, that proposes a comparison problem for students to explore. 
Aquarium Addition: In this lesson, the students’ learning is focused on using real world word problems to solve adding to problems with the result unknown. The students will be focusing on using manipulatives to create drawings to help them solve these problems. Furthermore, the students will be required to write the mathematical equations they used to solve the problem. 
Unit/Lesson Sequence

Macaroni Math: In this 6lesson unit, students will begin working on the fundamentals of subtraction using the takeaway model of subtraction in several different contexts (counting, sets, number line, balanced equations, and inverse of addition) using pasta shapes. They will learn to decompose numbers, explore the zero property, and the relation between addition and subtraction. Objects will be used to act out subtraction situations, and subtraction will be represented in pictures. They will compose and solve subtraction problems.
Individual Lessons
 Lesson 1: Recording Two Ways
 Using pasta shapes, students make sets and then subtract some away, recording the subtraction both vertically and horizontally. They draw a set of shapes and then subtract shapes by crossing them out, finally recording in both formats the subtraction represented in the drawing.
 Lesson 2: How Many Left?
 Students will work with the set model of subtraction, writing story problems and finding differences using sets, including subtraction of zero and all. Differences are recorded in chart format.
 Lesson 3: Where Will I Land?
 This lesson focuses on finding differences using the number line model. Students will be asked to predict differences and compose puzzles involving subtraction.
 Lesson 4: What Balance?
 This lesson uses the balance model to help students further explore the meaning of subtraction. They will start using subtraction facts to generate related addition facts, which bring to the foreground the conception of subtraction as the inverse of addition.
 Lesson 5: Who's in the Fact Family?
 This lesson continues exploring the relationship between addition and subtraction, as students find fact families using their problemsolving skill. This includes adding zero and alike addends.
 Lesson 6: What's the Difference?
 Students will use reasoning to find differences of numbers to 10, using calculators and addition charts. They will also play a game of concentration.

Comparing Connection Cubes: This 6 lesson unit focuses on the comparative mode of subtraction, and has students using connecting cubes to explore subtraction through five different models, counting, sets, number line, pan balance equations, and inverse of addition. Students will explore the relationship between addition and subtraction, use comparison in writing story problems, and practice subtraction facts and fact families. The lessons will build on and extend early understandings of counting, addition, and subtraction.
Individual Lessons
 Lesson 1: Counting Back and Counting On
 This lesson, which focuses on subtracting 1 from numbers to 10, begins with reading a counting book. The students model the numbers as the book is read. Then they make a chain of links and write in vertical and horizontal format the differences suggested by adding and subtracting one link at a time from their chains. Finally, they draw a chain showing one link being taken away and write in two formats the difference it represents.
 Lesson 2: Comparing Sets
 In this lesson students will be reviewing counting back by writing, estimating, and mentally computing whole number subtraction. They will count sets and record them in tables, which they will then use to draw conclusions. Students will also review the additive identity in the context of comparing sets.
 Lesson 3: Using the Number Line to Compare
 This lesson focuses on determining differences based on linear measurement, having students compare lengths using the number line. Students will then solve and create puzzles on number lines.
 Lesson 4: Balancing
 In this lesson students will explore subtraction through another model, the balance. The balance model leads naturally to recording equations. Students will write out in equation form the subtraction modeled on a pan balance, and then write out addition sentences that are from the same fact family.
 Lesson 5: Fact Families
 This lesson focuses on recording fact families, which students will use to explore the relationship between related addition and subtraction facts. Students will use connecting cubes and calculators to find missing addends, review the additive identity, and record fact families given either two addends or one addend and the sum.
 Lesson 6: Looking Back and Moving Forward
 This lesson reviews the work of the previous lessons, suggesting a framework for summative assessment. Students will use the knowledge and skills developed previously to demonstrate understanding while playing subtraction games.

Virtual Manipulative

Number Line Bars: A versatile tool that can be used to illustrate the operations of addition, subtraction, multiplication, and division. 
Number Line Arithmetic (Add, Subtract, Multiply, Divide): This virtual manipulative can be used to picture whole number operations:addition, subtraction, multiplication and division, carried out on a number line. 
ProblemSolving Task

The Pet Snake: The purpose of this task is for students to gain a better understanding of measurements with the example being the growth of a pet snake. 
Sharing Markers: These task types represent the Take From contexts for addition and subtraction (see Table 1 in the glossary of the CCSSM for all all addition and subtraction problem types). This task includes the three different problem types using the Take From context: result unknown, change unknown, and start unknown. Students need experience and practice with all three types. 
School Supplies: This task could be used for either instructional or assessment purposes, depending on where students are in their understanding of addition and how the teacher supports them. The solution shown is very terse; students' solution strategies are likely to be much more varied. 
Measuring Blocks: In this task, students work in pairs to measure a block using paperclips. 
Maria’s Marbles: Students benefit from encountering one problem type limited to small numbers and to develop strategies for that type of problem before encountering mixed sets of problems and larger numbers that distract the student from the problem itself. Over time they will be able to distinguish between types of problems in mixed sets and apply the appropriate strategy to solve each. 
Finding a Chair: These problems explicitly describe onetoone correspondences without using comparison language. Such problems are easier for students to solve than problems that use comparison language such as “How many more?” or “How many fewer.” 
Field Day Scarcity: The purpose of this task is for students to relate addition and subtraction problems to money in a context that introduces the concept of scarcity. Scarcity occurs when you want or need more than you can have. Students may want to buy everything but will discover that it not possible with only $7 and they will have to make decisions. 
Boys and Girls, Variation 2: This task represents the Put Together/Take Apart with both addends unknown context for addition and subtraction (see Table 1 in the glossary of the CCSSM for all addition and subtraction problem types). Once a student finds one correct answer, he/she can be encouraged to find another. Ask the student to use objects, pictures, or equations to represent each answer. 
Boys and Girls, Variation 1: Students may use either addition or subtraction to solve these types of word problems, with addition related to the action of putting together and subtraction related to the action of taking apart. Depending on how students think about these word problems, either is appropriate for the “addend unknown” problems. Seeing it both ways emphasizes the relationship between addition and subtraction. 
At the Park: This task includes three different problem types using the "Add To" context with a discrete quantity. 
Text Resource

Critical Areas and Changes in Grade 1: This document provides descriptions and examples of what each Mathematics Common Core standard means a Grade One student will know, understand, and be able to do. This "unpacking" of the standards provides instructional guidelines and was developed to assist North Carolina educators teach the Mathematics Common Core (Standard Course of Study). 
Teaching Idea

Introduction To Fact Families: Students will "invent" their own examples that demonstrate the commutative property of addition through handson activities. 
Rabbit Takeaway: This interactive Flash applet helps children understand the "take away" model of subtraction. Users choose starting numbers from within 10 or 20. A group of rabbits appears and the user is asked how many will remain if a certain number run away. Mousing over a clue button dims the number of runaways. After selecting the correct remainder, the rabbits run away, and the applet displays the number model and the word sentence that represent the problem. [Available for iPad and iPhone in the iTunes AppStore.] 
Instructional Technique

Video: Differentiating in Math Using Computer Games: This video show a teacher using a variety of tools and software programs to help the students have a better understanding of math. By incorporating technology in the classroom, the teacher can spend time with students who struggle to understand the concept while others can continue to pass levels in the games to move on to the next concept. 
Formative Assessment

Put Together/Take Apart (Both Addends Unknown) Word Problems: Students are asked to solve a Put Together/Take Apart (Both Addends Unknown) word problem using pencil and paper or other appropriate manipulatives. 
Red Birds and Blue Birds: Students are asked to solve two Put Together/Take Apart (Addend Unknown) word problems using pencil and paper or other appropriate manipulatives. 
Compare (Bigger Unknown) Word Problems: Students are asked to solve two Compare (Bigger Unknown) word problems using pencil and paper or other appropriate manipulatives. 
More Add To (Change Unknown) Problems: Students are asked to solve two Add To (Change Unknown) word problems using pencil and paper or other appropriate manipulatives. 
How Many More Stickers?: Students are asked to solve a Compare (Difference Unknown) word problem using pencil and paper or other appropriate manipulatives. 
Add To (Result Unknown) Word Problems: Students are asked to solve two Add To (Result Unknown) word problems using pencil and paper or other appropriate manipulatives. 
Add To (Start Unknown) Word Problems: Students are asked to solve two Add To (Start Unknown) word problems using pencil and paper or other appropriate manipulatives. 
Put Together/Take Apart (Total Unknown): Students are asked to solve two Put Together/Take Apart (Total Unknown) word problems using pencil and paper or other appropriate manipulatives. 
How Many M&Ms?: Students are asked to solve two Compare problems focusing on the terms more than and fewer than. 
Trains and Jump Ropes: Students are asked to solve two Compare problems focusing on the terms more than and fewer than. 
Birds on a Branch: Students are asked to solve two Take From (Change Unknown) word problems using pencil and paper or other appropriate manipulatives. 
Take From (Result Unknown): Students are asked to solve two Take From (Result Unknown) word problems using pencil and paper or other appropriate manipulatives. 
The Cupcake Problem: Students are asked to solve two Take From (Start Unknown) word problems using pencil and paper or other appropriate manipulatives. 
Fish in a Pond: Students solve a Take From (Start Unknown) word problem. 
Add To (Change Unknown) Word Problems: Students are asked to solve two Add To (Change Unknown) word problems using pencil and paper or other appropriate manipulatives. 
Put Together/Take Apart (Addend Unknown) Word Problem: Students are asked to solve two Put Together/Take Apart (Addend Unknown) word problems using pencil and paper or other appropriate manipulatives. 
Take From (Change Unknown) Word Problems: Students are asked to solve two Take From (Change Unknown) word problems using pencil and paper or other appropriate manipulatives. 
Take From (Start Unknown): Students are asked to solve two Take From (Start Unknown) word problems using pencil and paper or other appropriate manipulatives. 
Compare (Difference Unknown) Word Problems: Students are asked to solve two Compare (Difference Unknown) word problems within 20 using pencil and paper or other appropriate manipulatives. 
Compare (Smaller Unknown) Word Problems: Students are asked to solve two Compare (Smaller Unknown) word problems using pencil and paper or other appropriate manipulatives. 
Lesson Study Resource Kit

Laying the Groundwork: A K2 Lesson Study Resource Kit for Introducing Students to Inverse Operations.: This K2 mathematics resource kit is designed to assist teams of teachers engaged in lesson study with essential background information and exemplary lesson resources to construct an instructional unit that prepares students for achieving an understanding of inverse operations that corresponds to the Common Core State Standards for Mathematics. Included in this resource kit are: Background research on the importance of preparing elementary students for understanding the concept of inverse operations, Formative assessment tasks related to this topic, A "Developmental Story" that illustrates a learning progression for putting students on a path to achieving adult learning expectations of this concept, An adaptable model lesson for teaching the concept of inverse operations to students in K2, and Examples of student responses to problems posed in the exemplary lesson.
Related Resource Types
 + Macaroni Math + : In this 6lesson unit, students will begin working on the fundamentals of subtraction using the takeaway model of subtraction in several different contexts (counting, sets, number line, balanced equations, and inverse of addition) using pasta shapes. They will learn to decompose numbers, explore the zero property, and the relation between addition and subtraction. Objects will be used to act out subtraction situations, and subtraction will be represented in pictures. They will compose and solve subtraction problems.<br /> <br /><b>Individual Lessons</b><br /> <ul style="liststyle: none outside none;"> <li><a href="http://illuminations.nctm.org/Lesson.aspx?id=677" target="_blank">Lesson 1: Recording Two Ways</a></li> <ul style="liststyle: none outside none;"><li> Using pasta shapes, students make sets and then subtract some away, recording the subtraction both vertically and horizontally. They draw a set of shapes and then subtract shapes by crossing them out, finally recording in both formats the subtraction represented in the drawing. </li></ul> <li><a href="http://illuminations.nctm.org/Lesson.aspx?id=679" target="_blank">Lesson 2: How Many Left?</a></li> <ul style="liststyle: none outside none;"><li> Students will work with the set model of subtraction, writing story problems and finding differences using sets, including subtraction of zero and all. Differences are recorded in chart format. </li></ul> <li><a href="http://illuminations.nctm.org/Lesson.aspx?id=683" target="_blank">Lesson 3: Where Will I Land?</a></li> <ul style="liststyle: none outside none;"><li> This lesson focuses on finding differences using the number line model. Students will be asked to predict differences and compose puzzles involving subtraction. </li></ul> <li><a href="http://illuminations.nctm.org/Lesson.aspx?id=686" target="_blank">Lesson 4: What Balance?</a></li> <ul style="liststyle: none outside none;"><li> This lesson uses the balance model to help students further explore the meaning of subtraction. They will start using subtraction facts to generate related addition facts, which bring to the foreground the conception of subtraction as the inverse of addition. </li></ul> <li><a href="http://illuminations.nctm.org/Lesson.aspx?id=689" target="_blank">Lesson 5: Who's in the Fact Family?</a></li> <ul style="liststyle: none outside none;"><li> This lesson continues exploring the relationship between addition and subtraction, as students find fact families using their problemsolving skill. This includes adding zero and alike addends. </li></ul> <li><a href="http://illuminations.nctm.org/Lesson.aspx?id=691" target="_blank">Lesson 6: What's the Difference?</a></li> <ul style="liststyle: none outside none;"><li> Students will use reasoning to find differences of numbers to 10, using calculators and addition charts. They will also play a game of concentration. </li></ul> </ul>
 + Comparing Connection Cubes + : This 6 lesson unit focuses on the comparative mode of subtraction, and has students using connecting cubes to explore subtraction through five different models, counting, sets, number line, pan balance equations, and inverse of addition. Students will explore the relationship between addition and subtraction, use comparison in writing story problems, and practice subtraction facts and fact families. The lessons will build on and extend early understandings of counting, addition, and subtraction.<br /> <br /><b>Individual Lessons</b><br /> <ul style="liststyle: none outside none;"> <li><a target="_blank" href="http://illuminations.nctm.org/Lesson.aspx?id=310">Lesson 1: Counting Back and Counting On </a></li> <ul style="liststyle: none outside none;"><li> This lesson, which focuses on subtracting 1 from numbers to 10, begins with reading a counting book. The students model the numbers as the book is read. Then they make a chain of links and write in vertical and horizontal format the differences suggested by adding and subtracting one link at a time from their chains. Finally, they draw a chain showing one link being taken away and write in two formats the difference it represents. </li></ul> <li><a target="_blank" href="http://illuminations.nctm.org/Lesson.aspx?id=315">Lesson 2: Comparing Sets </a></li> <ul style="liststyle: none outside none;"><li> In this lesson students will be reviewing counting back by writing, estimating, and mentally computing whole number subtraction. They will count sets and record them in tables, which they will then use to draw conclusions. Students will also review the additive identity in the context of comparing sets. </li></ul> <li><a target="_blank" href="http://illuminations.nctm.org/Lesson.aspx?id=321">Lesson 3: Using the Number Line to Compare </a></li> <ul style="liststyle: none outside none;"><li> This lesson focuses on determining differences based on linear measurement, having students compare lengths using the number line. Students will then solve and create puzzles on number lines. </li></ul> <li><a target="_blank" href="http://illuminations.nctm.org/Lesson.aspx?id=326">Lesson 4: Balancing </a></li> <ul style="liststyle: none outside none;"><li> In this lesson students will explore subtraction through another model, the balance. The balance model leads naturally to recording equations. Students will write out in equation form the subtraction modeled on a pan balance, and then write out addition sentences that are from the same fact family. </li></ul> <li><a target="_blank" href="http://illuminations.nctm.org/Lesson.aspx?id=329">Lesson 5: Fact Families </a></li> <ul style="liststyle: none outside none;"><li> This lesson focuses on recording fact families, which students will use to explore the relationship between related addition and subtraction facts. Students will use connecting cubes and calculators to find missing addends, review the additive identity, and record fact families given either two addends or one addend and the sum. </li></ul> <li><a target="_blank" href="http://illuminations.nctm.org/Lesson.aspx?id=338">Lesson 6: Looking Back and Moving Forward </a></li> <ul style="liststyle: none outside none;"><li> This lesson reviews the work of the previous lessons, suggesting a framework for summative assessment. Students will use the knowledge and skills developed previously to demonstrate understanding while playing subtraction games. </li></ul> </ul>
 + Number Line Bars + : A versatile tool that can be used to illustrate the operations of addition, subtraction, multiplication, and division.
 + Out of Sight Missing Addends + : Students will learn how to use manipulatives to solve missing addends in math problems.
 + Subtraction Race + : OBJECTIVE: Through a game promoting physical activity, students will practice subtracting numbers with a difference between 1 and 10.
 + A Family of Facts + : In this handson lesson plan, students use the analogy of a literal family (including cutouts of boys, girls, and houses) to learn about fact families and the inverse nature of addition and subtraction.
 + Critical Areas and Changes in Grade 1 + : This document provides descriptions and examples of what each Mathematics Common Core standard means a Grade One student will know, understand, and be able to do. This "unpacking" of the standards provides instructional guidelines and was developed to assist North Carolina educators teach the Mathematics Common Core (Standard Course of Study).
 + Bunny Addition + : This lesson integrates language arts, music, and math. The children will listen to the story <cite>Count on Bunnies</cite>. They will be given the opportunity to act out the story and solve bunny equations. After listening to the song "Five Young Rabbits," the children will take turns being rabbits and pantomiming the actions as the class sings. The children will combine the rabbits at the end of each verse to see how many rabbits have been added. Then they will work in pairs to create their own rabbit equations.<br />
 + An Apple of Day + : This is a handson lesson which uses apples to introduce the concept of "half" and to teach simple addition.
 + Supermarket Sweep Day 2 + : Students will participate in a supermarket game and follow a shopping list. Students will compare the quantity of items "purchased" and graph results. Students will also learn a song about shopping in a supermarket.
 + Introduction To Fact Families + : Students will "invent" their own examples that demonstrate the commutative property of addition through handson activities.
 + Links Away: Hopping Backwards on the Number Line + : <p>This lesson uses the number line model to teach students how to generate differences. First, the teacher will demonstrate this by having students hop to subtract numbers on a physical number line (such as carpet squares or a shower curtain marked appropriately). Students will also investigate whether the commutative property holds for subtraction.</p>
 + Video: Differentiating in Math Using Computer Games + : This video show a teacher using a variety of tools and software programs to help the students have a better understanding of math. By incorporating technology in the classroom, the teacher can spend time with students who struggle to understand the concept while others can continue to pass levels in the games to move on to the next concept.
 + Number Line Arithmetic (Add, Subtract, Multiply, Divide) + : This virtual manipulative can be used to picture whole number operations:addition, subtraction, multiplication and division, carried out on a number line.
 + Math Place Value + : The students will use ten frames to show place value of two digit numbers 0100. Students will use different manipulatives to show place value of two digit numbers. The students will be able to recognize the correct place value for a two digit numbers.
 + The Pet Snake + : The purpose of this task is for students to gain a better understanding of measurements with the example being the growth of a pet snake.
 + Sharing Markers + : These task types represent the Take From contexts for addition and subtraction (see Table 1 in the glossary of the CCSSM for all all addition and subtraction problem types). This task includes the three different problem types using the Take From context: result unknown, change unknown, and start unknown. Students need experience and practice with all three types.
 + School Supplies + : This task could be used for either instructional or assessment purposes, depending on where students are in their understanding of addition and how the teacher supports them. The solution shown is very terse; students' solution strategies are likely to be much more varied.
 + Measuring Blocks + : In this task, students work in pairs to measure a block using paperclips.
 + Maria’s Marbles + : Students benefit from encountering one problem type limited to small numbers and to develop strategies for that type of problem before encountering mixed sets of problems and larger numbers that distract the student from the problem itself. Over time they will be able to distinguish between types of problems in mixed sets and apply the appropriate strategy to solve each.
 + Finding a Chair + : These problems explicitly describe onetoone correspondences without using comparison language. Such problems are easier for students to solve than problems that use comparison language such as “How many more?” or “How many fewer.”
 + Field Day Scarcity + : The purpose of this task is for students to relate addition and subtraction problems to money in a context that introduces the concept of scarcity. Scarcity occurs when you want or need more than you can have. Students may want to buy everything but will discover that it not possible with only $7 and they will have to make decisions.
 + Boys and Girls, Variation 2 + : This task represents the Put Together/Take Apart with both addends unknown context for addition and subtraction (see Table 1 in the glossary of the CCSSM for all addition and subtraction problem types). Once a student finds one correct answer, he/she can be encouraged to find another. Ask the student to use objects, pictures, or equations to represent each answer.
 + Boys and Girls, Variation 1 + : Students may use either addition or subtraction to solve these types of word problems, with addition related to the action of putting together and subtraction related to the action of taking apart. Depending on how students think about these word problems, either is appropriate for the “addend unknown” problems. Seeing it both ways emphasizes the relationship between addition and subtraction.
 + At the Park + : This task includes three different problem types using the "Add To" context with a discrete quantity.
 + Cookie Subtraction + : In this lesson, the teacher shares the book, "Mmm... Cookie Simple Subtraction". The students follow along by representing the problems in the book with cookie manipulatives and recording the equations for each problem. The lesson incorporates a variety of subtraction problem types.
 + Addition Stories at the Food Store + : In this lesson, students will solve addition whole number word problems (within 20) with realworld scenarios by using manipulatives or drawings and equations.
 + Flower Power Flower Company MEA & STEAM* Activity + : <p>This STEAM (Science, Technology, Engineering, Art, and Math) lesson has been designed around a ModelEliciting Activity.</p> <p>This Model Eliciting Activity (MEA) is written at a 1st grade level. The Flower Power MEA provides students with an real world problem in which they must work as a team to design a plan to select the best flower arrangement for a special event. The resource was primarily designed as an MEA so the time and teacher instructions are primarily based on the MEA. The additional activities will take several hours of instruction but include watching and discussing a video about the parts of plants, reading a book, and discussing the art in the book as well as additional art by the book author/illustrator.</p>
 + Solving Word Problems Using Story Structure + : In this lesson, students will learn how to use their knowledge of beginning, middle, and end to solve word problems that include result unknown, change unknown, and start unknown. They will learn how to use a modified story map to write an equation to represent the problem.
 + Word Problem Lesson + : In this lesson, students will be able to solve compare word problems.
 + Making 11 + : In this lesson students use manipulatives to discover how to build the number 11. This lesson is great for novice teachers or for teachers who have changed to 1st grade.
 + Quilt Squares + : Students will use pattern blocks to create a quilt square for the Quick Quilters Society. They will have to consider information on a data chart to help them create their squares. They will have to add up the cost to make their square, too.
 + Fill It Up  Piñatas! + : <p>This is an MEA lesson that focuses on students' problem solving skills. After reading a story about what is in a piñata, students are asked to help a company find the best way to fill a piñata. It focuses on math skills, including counting and recognizing numbers to 120.</p>
 + An Amazing Sunny Day Story + : In this lesson, students are shown a picture of a beach scene. They are asked to identify groups of things within the picture. There are three predetermined groups of ten with noticeable parts (people, starfish, coconuts). Using the picture, students will identify a group of ten, create an addition equation for the parts, and transfer the equation into sentences to tell the story.
 + Pete's Groovy Button Problems + : This lesson uses a familiar character, Pete the Cat, that proposes a comparison problem for students to explore.
 + Aquarium Addition + : In this lesson, the students’ learning is focused on using real world word problems to solve adding to problems with the result unknown. The students will be focusing on using manipulatives to create drawings to help them solve these problems. Furthermore, the students will be required to write the mathematical equations they used to solve the problem.
 + Put Together/Take Apart (Both Addends Unknown) Word Problems + : Students are asked to solve a Put Together/Take Apart (Both Addends Unknown) word problem using pencil and paper or other appropriate manipulatives.
 + Red Birds and Blue Birds + : Students are asked to solve two Put Together/Take Apart (Addend Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + Compare (Bigger Unknown) Word Problems + : Students are asked to solve two Compare (Bigger Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + More Add To (Change Unknown) Problems + : Students are asked to solve two Add To (Change Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + How Many More Stickers? + : Students are asked to solve a Compare (Difference Unknown) word problem using pencil and paper or other appropriate manipulatives.
 + Add To (Result Unknown) Word Problems + : Students are asked to solve two Add To (Result Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + Add To (Start Unknown) Word Problems + : Students are asked to solve two Add To (Start Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + Put Together/Take Apart (Total Unknown) + : Students are asked to solve two Put Together/Take Apart (Total Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + How Many M&Ms? + : Students are asked to solve two Compare problems focusing on the terms <em>more than </em>and<em> fewer than</em>.
 + Trains and Jump Ropes + : Students are asked to solve two Compare problems focusing on the terms <em>more than </em>and<em> fewer than.</em>
 + Birds on a Branch + : Students are asked to solve two Take From (Change Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + Take From (Result Unknown) + : Students are asked to solve two Take From (Result Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + The Cupcake Problem + : Students are asked to solve two Take From (Start Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + Fish in a Pond + : Students solve a Take From (Start Unknown) word problem.
 + Add To (Change Unknown) Word Problems + : Students are asked to solve two Add To (Change Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + Put Together/Take Apart (Addend Unknown) Word Problem + : Students are asked to solve two Put Together/Take Apart (Addend Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + Take From (Change Unknown) Word Problems + : Students are asked to solve two Take From (Change Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + Take From (Start Unknown) + : Students are asked to solve two Take From (Start Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + Compare (Difference Unknown) Word Problems + : Students are asked to solve two Compare (Difference Unknown) word problems within 20 using pencil and paper or other appropriate manipulatives.
 + Compare (Smaller Unknown) Word Problems + : Students are asked to solve two Compare (Smaller Unknown) word problems using pencil and paper or other appropriate manipulatives.
 + Rabbit Takeaway + : This interactive Flash applet helps children understand the "take away" model of subtraction. Users choose starting numbers from within 10 or 20. A group of rabbits appears and the user is asked how many will remain if a certain number run away. Mousing over a clue button dims the number of runaways. After selecting the correct remainder, the rabbits run away, and the applet displays the number model and the word sentence that represent the problem. [Available for iPad and iPhone in the iTunes AppStore.]
 + Laying the Groundwork: A K2 Lesson Study Resource Kit for Introducing Students to Inverse Operations. + : This K2 mathematics resource kit is designed to assist teams of teachers engaged in lesson study with essential background information and exemplary lesson resources to construct an instructional unit that prepares students for achieving an understanding of inverse operations that corresponds to the Common Core State Standards for Mathematics. Included in this resource kit are: Background research on the importance of preparing elementary students for understanding the concept of inverse operations, Formative assessment tasks related to this topic, A "Developmental Story" that illustrates a learning progression for putting students on a path to achieving adult learning expectations of this concept, An adaptable model lesson for teaching the concept of inverse operations to students in K2, and Examples of student responses to problems posed in the exemplary lesson.
14 Student Resources
 Number Line Bars: A versatile tool that can be used to illustrate the operations of addition, subtraction, multiplication, and division.
 Introduction To Fact Families: Students will "invent" their own examples that demonstrate the commutative property of addition through handson activities.
 Rabbit Takeaway: This interactive Flash applet helps children understand the "take away" model of subtraction. Users choose starting numbers from within 10 or 20. A group of rabbits appears and the user is asked how many will remain if a certain number run away. Mousing over a clue button dims the number of runaways. After selecting the correct remainder, the rabbits run away, and the applet displays the number model and the word sentence that represent the problem. [Available for iPad and iPhone in the iTunes AppStore.]
 The Pet Snake: The purpose of this task is for students to gain a better understanding of measurements with the example being the growth of a pet snake.
 Sharing Markers: These task types represent the Take From contexts for addition and subtraction (see Table 1 in the glossary of the CCSSM for all all addition and subtraction problem types). This task includes the three different problem types using the Take From context: result unknown, change unknown, and start unknown. Students need experience and practice with all three types.
 School Supplies: This task could be used for either instructional or assessment purposes, depending on where students are in their understanding of addition and how the teacher supports them. The solution shown is very terse; students' solution strategies are likely to be much more varied.
 Measuring Blocks: In this task, students work in pairs to measure a block using paperclips.
 Maria’s Marbles: Students benefit from encountering one problem type limited to small numbers and to develop strategies for that type of problem before encountering mixed sets of problems and larger numbers that distract the student from the problem itself. Over time they will be able to distinguish between types of problems in mixed sets and apply the appropriate strategy to solve each.
 Finding a Chair: These problems explicitly describe onetoone correspondences without using comparison language. Such problems are easier for students to solve than problems that use comparison language such as “How many more?” or “How many fewer.”
 Field Day Scarcity: The purpose of this task is for students to relate addition and subtraction problems to money in a context that introduces the concept of scarcity. Scarcity occurs when you want or need more than you can have. Students may want to buy everything but will discover that it not possible with only $7 and they will have to make decisions.
 Boys and Girls, Variation 2: This task represents the Put Together/Take Apart with both addends unknown context for addition and subtraction (see Table 1 in the glossary of the CCSSM for all addition and subtraction problem types). Once a student finds one correct answer, he/she can be encouraged to find another. Ask the student to use objects, pictures, or equations to represent each answer.
 Boys and Girls, Variation 1: Students may use either addition or subtraction to solve these types of word problems, with addition related to the action of putting together and subtraction related to the action of taking apart. Depending on how students think about these word problems, either is appropriate for the “addend unknown” problems. Seeing it both ways emphasizes the relationship between addition and subtraction.
 At the Park: This task includes three different problem types using the "Add To" context with a discrete quantity.
 Number Line Arithmetic (Add, Subtract, Multiply, Divide): This virtual manipulative can be used to picture whole number operations:addition, subtraction, multiplication and division, carried out on a number line.
12 Parent Resources
 Number Line Bars: A versatile tool that can be used to illustrate the operations of addition, subtraction, multiplication, and division.
 The Pet Snake: The purpose of this task is for students to gain a better understanding of measurements with the example being the growth of a pet snake.
 Sharing Markers: These task types represent the Take From contexts for addition and subtraction (see Table 1 in the glossary of the CCSSM for all all addition and subtraction problem types). This task includes the three different problem types using the Take From context: result unknown, change unknown, and start unknown. Students need experience and practice with all three types.
 School Supplies: This task could be used for either instructional or assessment purposes, depending on where students are in their understanding of addition and how the teacher supports them. The solution shown is very terse; students' solution strategies are likely to be much more varied.
 Measuring Blocks: In this task, students work in pairs to measure a block using paperclips.
 Maria’s Marbles: Students benefit from encountering one problem type limited to small numbers and to develop strategies for that type of problem before encountering mixed sets of problems and larger numbers that distract the student from the problem itself. Over time they will be able to distinguish between types of problems in mixed sets and apply the appropriate strategy to solve each.
 Finding a Chair: These problems explicitly describe onetoone correspondences without using comparison language. Such problems are easier for students to solve than problems that use comparison language such as “How many more?” or “How many fewer.”
 Field Day Scarcity: The purpose of this task is for students to relate addition and subtraction problems to money in a context that introduces the concept of scarcity. Scarcity occurs when you want or need more than you can have. Students may want to buy everything but will discover that it not possible with only $7 and they will have to make decisions.
 Boys and Girls, Variation 2: This task represents the Put Together/Take Apart with both addends unknown context for addition and subtraction (see Table 1 in the glossary of the CCSSM for all addition and subtraction problem types). Once a student finds one correct answer, he/she can be encouraged to find another. Ask the student to use objects, pictures, or equations to represent each answer.
 Boys and Girls, Variation 1: Students may use either addition or subtraction to solve these types of word problems, with addition related to the action of putting together and subtraction related to the action of taking apart. Depending on how students think about these word problems, either is appropriate for the “addend unknown” problems. Seeing it both ways emphasizes the relationship between addition and subtraction.
 At the Park: This task includes three different problem types using the "Add To" context with a discrete quantity.
 Number Line Arithmetic (Add, Subtract, Multiply, Divide): This virtual manipulative can be used to picture whole number operations:addition, subtraction, multiplication and division, carried out on a number line.
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