Open Number Lines Unit of Study: Strengthening Critical Area: Understanding Place Value to Add and Subtract Global Concept Guide: 2 of 3

You may have noticed that Unit 16’s GCG’s look different from the previous units. Unit 16 was provided as a way to strengthen student understanding of the critical area place value. Your student’s performance on the Unit Assessment and Performance Task will be your guide for the activities you select as you progress through this unit.

Content Development  An open number line is a number line with no numbers or markers. It is a visual representation to track student thinking with mental computation. Using an open number line, students will be able to show the addition or subtraction of tens and ones. Before students use an open number line, they need multiple experiences with a number line with markers and counting on and back within 100.  Click here for more information on open number lines.here

 The Problem: Keisha was trying to set her record for juggling a soccer ball. On her first attempt, she juggled the ball a total of 57 times before it hit the ground. On her second attempt, she only got a total of 29 juggles. Combining both her first and second attempts, how many times did she juggle the ball in total?  When using a number line flexibly, students may choose to solve this problem in any number of ways. Here are three different representations of how students thought differently to solve the problem. The first solution, for example, shows a student who counts on from 57, first by 10ʼs. After skipping forward by 30 (three jumps of 10), the student realizes that she needs to compensate by hopping back by one to arrive at the correct answer

Day 1 Essential Question: How can I use an open number line to help add? Adding on an Open Number LineAdding on an Open Number Line is a teacher resource to help with modeling using an open number line.  Use open number lines to solve problems on Go Math Getting Ready for Grade 2 Lesson 9 Add Two-Digit Numbers p. P267 – P268. Students must use number line to model the addition problem and then record the sum. Teachers should be observing students to see which strategies students are using to add on to find totals. By the end of Day 1, students will be able to record addition on open number lines.

Day 2 Essential Question: How can using an open number line help me to solve addition and subtraction problems?  Day 1 Focus: on how to use the open number line and how it can be used for addition and subtraction problems.  Open Number Line Lesson Scroll down to A9 Act 3 Introducing the Open Number Line. This lesson the open number line is introduced and developed in Activities 3-5. This is a 2 nd grade lesson so the number involved are outside of 1 st grade content limits, use these problems with the concepts developed in the lesson. Open Number Line Lesson problems By the end of Day 2, students will be able to determine important information in problem solving scenarios and can model on an open number line.

Day 3 Essential Question: How can I strategically break apart a number to help me add and subtract 2-digit numbers?  Day 3 focuses on the various ways to decompose a number to add and subtract with the open number line. LearnZillion begin video at 3:40.LearnZillion  Use problem solving scenarios to have students solve using open number line— Number Line Problem Solving.Number Line Problem Solving  Provide multiple opportunities for students to share how they used the open number line. It is important for students to see the various ways to decompose a number as well as explore other student’s way of thinking. Exit Ticket: Assessment Task 13 students will model breaking apart two 2-digit numbers, use a number line to add and then provide a solution.Assessment Task 13 By the end of Day 3, students will be able to efficiently break apart a 2- digit number to add and subtract on an open number line.

Enrich/Reteach/Intervention Reteach/Intervention  Provide students with addition number sentences listed in the tasks below. Students will solve for the sum utilizing an open number line. The teacher should emphasize the jumps of tens and ones to reinforce place value. Also, provide students practice with subtraction problems, based on the student needs.  Task 1 - Ten Frames Task 1Ten Frames Enrich  Provide students with addition and subtraction problems and blank open number lines. The students will use this tool to solve the problem but extend their thinking by encouraging more than one way. Students can compare their number lines and find more ways to decompose the numbers.  Provide students with a sample open number line that represents an addition or subtraction problem. Students can create a problem scenario to match the open number line.