1. Modeling Addition and Subtraction
Unit of Study: Strengthening Critical Area: Understanding Place Value to Add and Subtract
Global Concept Guide: 1 of 2

2. Content Development
This GCG revisits the use of tools/manipulatives and quick pictures to help add and subtract.
“First Grade students use concrete materials, models, and drawings and place value strategies to add within 100. They do so by being flexible with numbers as they use the base-ten system to solve problems. The standard algorithm of carrying or borrowing is neither an expectation or focus in First Grade.” (NCDPI, 2012, p.21)
“It is important for students to understand if they are adding a number that has 10s to a number with 10s, they will have more tens than they started with; the same applies to the ones. Also, students should be able to apply their place value skills to decompose numbers. For example, can be thought of 1 ten and 7 ones plus 1 ten and 2 ones. (CCSS Flipbook, 2011, p. 23)”

3. Day 1 Literature Lesson: A Fair Bear Share
This lesson uses the literature connection, A Fair Bear Share by Stuart Murphy. Students will engage in the story and can complete related problems using models. Students will build or draw models on the provided document. The models may include ten frames, base 10 blocks, snap cubes, etc…
Possible Journal Extension: The sum of a two-digit number and one-digit number is 43. What might the numbers be? Justify your thinking with a math tool.
Students can use models and tools to help solve this task and share their solutions with one another.
Possible Extension: Who’s got the most?

4. Day 2 Lesson: Game of Tens and Ones
In the provided lesson, students will play a game with die and hundreds chart to add and subtract within The provided lesson outlines how to introduce this game and student responses.
It is essential students have access to a variety of tools to help complete this task. This day continues the foundation of tools and pictures to understand place value in connection with addition and subtraction.
Possible Journal Extension: What two numbers have a sum of 81? Students can share responses with each other.

5. Day 3 Lesson: Race to a Flat
Although children may know how to count to 100, they sometimes have difficulty in bridging the decades—that is, in continuing the counting from one decade to the next. For example, when counting “...56, 57, 58, 59...” a child may fail to remember that 60 comes next in the sequence and may instead name some other multiple of ten. Race for a Flat reinforces children’s understanding of the order in which numbers are sequenced from one decade to the next.

6. Day 4 Lesson: Race to Clear a Mat
Race to Clear the Mat as the “opposite” of the game Race for a Flat.Race to Clear the Mat requires children to model the process of subtracting one- or two-digit numbers from one-, two-, or three-digit numbers. Children are sometimes asked to regroup, or “trade,” from one place-value position to another in order to subtract before they fully understand the concept of subtraction. By experiencing the subtraction operation as they do in this game, children deepen their conceptualization of the meaning of subtraction and why it is sometimes necessary to regroup.

7. Reteach/Intervention
Using ten frames to add and subtract
This reteach task will support understanding in addition and subtraction with the tool, ten frames. Use the task provided below and provide students with additional problems similar to the task.
Task 3
Ten Frames Blackline Master
Using tools (base 10 blocks) and quick pictures to add and subtract
Use the task provided below to reteach using tools to complete a problem solving situation. Use similar problems as needed for your students.
Task 1
Task 2

8. Enrich Enrich Target Sum/Cover Up
These games can be used for enrichment for students. Students will be able solve addition and subtraction problems. Students can use tools and quick pictures to help them solve these problems.
The Cover Up game can be used for reteach and enrich. Game board #1 can be used for a reteach group and game board #2 can be used for enrich. A third game board is blank and can be used based on your student needs.
Directions for Target Sum and Cover Up
Target Sum Game Board
Target Sum Digit Cards
Cover Up Game Board
Cover Up Cards

9. Literature for your Classroom Library