# Gr. 1 Unit: Use Place Value Understanding & Properties of Operations to Add & Subtract

### UNIT OVERVIEW

This unit allows students in Grade 1 to build on their understanding of place value that began in Kindergarten with numbers 11-19, and extend this understanding to addition within 100. In Kindergarten, students kept each count as a single count as they explored a set of 10 objects and leftovers. In this unit, students in Grade 1 are expected to recognize that a set of 10 objects is a unit called a “ten” (unitizing). Students in First Grade also use concrete materials, models, drawings, and place value strategies to add within 100 by being flexible with numbers as they solve problems. It is the expectation that students in Grade 1 also engage in mental calculation, such as mentally finding ten more or ten less than a given two-digit number without having to count by ones. In Grade 1 students are not expected to compute the differences of two-digit numbers other than multiples of ten. Deferring such work until Grade 2 allows two-digit subtraction with and without decomposing to occur in close succession, highlighting the similarity between these two cases. It is important to note that the standard algorithm of carrying or borrowing is neither an expectation nor a focus in Grade 1.

**Essential Questions:**

- How does using the base ten system make it easier for me to count?
- How does the place value system work?
- How do I determine the most efficient way to represent a number (pictorial, symbolic, with objects) for a given situation?
- In what ways can items be grouped to make exchanges for unit(s) of higher value??
- How does the position of a digit in a number affect its value?
- In what ways can numbers be composed and decomposed?
- How are place value patterns repeated in numbers?
- How can place value properties aid computation?

A question is essential when it stimulates multi-layered inquiry, provokes deep thought and lively discussion, requires students to consider alternatives and justify their reasoning, encourges re-thinking of big ideas, makes meaningful connections with prior learning, and provides students with opportunities to apply problem-solving skills to authentic situations.

**UNIT LESSON:**

Use place value understanding and properties of operations to add and subtract

Additional information such as Teachers Notes, Enduring Understandings,Content Emphasis by Cluster, Focus Standards, Possible Student Outcomes, Essential Skills and Knowledge Statements and Clarifications, and Interdisciplinary Connections can be found in this Lesson Unit.

**AVAILABLE MODEL LESSON PLANS**

The lesson plan(s) have been written with specific standards in mind. Each model lesson plan is only a MODEL - one way the lesson could be developed. We have NOT included any references to the timing associated with delivering this model. Each teacher will need to make decisions related ot the timing of the lesson plan based on the learning needs of students in the class. The model lesson plans are designed to generate evidence of student understanding.

This chart indicates one or more lesson plans which have been developed for this unit. Lesson plans are being written and posted on the Curriculum Management System as they are completed. Please check back periodically for additional postings.

CCSC Alignment: 1.NBT.C.5

Students identify counting by 10s as the most efficient way to count a larger quantity of objects up to 99, identify patterns in numbers to help them identify 10 more and 10 less, build two-digit numbers to compare quantities that are 10 more and 10 less, and mentally find 10 more and 10 less than a given number.

**AVAILABLE MODEL LESSON SEEDS**

The lesson seed(s) have been written with specific standards in mind. These suggested activity/activities are not intended to be prescriptive, exhaustive, or sequential; they simply demonstrate how specific content can be used to help students learn the skills described in the standards. Seeds are designed to give teachers ideas for developing their own activities in order to generate evidence of student understanding.

This chart indicates one or more lesson seeds which have been developed for this unit. Lesson seeds are being written and posted on the Curriculum Management System as they are completed. Please check back periodically for additional postings.

CCSC Alignnment: 1.NBT.C.5

Students strengthen and reinforce their understanding of number patterns on the hundreds chart and use them to find 10 more or 10 less than a given number.