I have used each of these resources with my own students and have had great success with them. Enjoy!
These resources cover each standard within the second grade common core area of Operations and Algebraic thinking. The resources include 30+ pages of examples, posters, and practice sheets for students. Common Core Standards covered in this resources include:
Represent and solve problems involving addition and subtraction.
Use addition and subtraction within 100 to solve one- and two-step word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.
Add and subtract within 20.
Fluently add and subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.
Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counting them by 2s; write an equation to express an even number as a sum of two equal addends.
Use addition to find the total number of objects arranged in rectangular arrays with up to 5 rows and up to 5 columns; write an equation to express the total as a sum of equal addends.
* Please note that some specific strategies used in these resources (bar models, etc) have been adapted from "Math in Focus". I love using this resource and have had great success with it. Just an FYI! :)