Peter Zahn 
Let’s Recycle [PDF ebook] 
Represent and Solve Addition Problems

Algebra is a foundational concept in the study of mathematics, and readers will delight in learning the principles of operations and algebraic thinking in a relatable and engaging way. Topics such as adding and subtracting within 20, using algebraic principles to solve equations and word problems, and understanding the relationship between addition and subtraction will give beginning math students a firm grasp on basic math concepts. Early readers will learn how to add three whole numbers while also understanding why recycling is so important for the environment. This volume satisfies CCSS Math Standard 1.OA.A.2. This book should be paired with "We Can Recycle" (9781477721780) from the Info Max Math Readers Program to provide the alternative point of view on the same topic.