Looking for number line practice worksheets to align with your Common Core math instruction? This file will help you teach your students to add and subtract on Open Number Line using Counting Up and Counting Back, Friendly Numbers, Place Value, and Counting Up to Subtract strategies. Included are helpful teaching hints, common student errors, and 22 (yes, twenty-two!) two-sided worksheets designed to build students' addition and subtraction fluency with two and three digit numbers. Aligned to Common Core Number and Operations in Base Ten and an excellent transition/reteach for students missing this key instruction in upper grades. Each worksheet has teacher reminders as well as a sample problem.