Build Expressions Equal to Twenty The Snap Blocks™ tool is an engaging way for students to make sense of the concept of equality and begin to make generalizations that will inform their algebraic thinking. Students will understand the meaning of the equal sign and the concept of equivalence in this math lesson plan. They will explore relational thinking by noting relationships between two sides of an equation.
Sample Lesson Plan
Objective: 
Students are able to prove that two expressions are equivalent by recognizing smaller parts of the expressions that are equivalent. 
Background: 
Students should have an understanding of basic addition number facts within 20. 
Instruction: 

Common Core State Standards
Grade 
ID 
Domain 
Cluster 
Standard 
2 
2.NBT.5 
Number and Operations in Base Ten 
Use place value understanding and properties of operations to add and subtract. 
Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction. 
2 
2.OA.1 
Operations & Algebraic Thinking 
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. 
2 
2.OA.2 
Operations & Algebraic Thinking 
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 onedigit numbers. 
2 
2.SMP.2 
Mathematical Practices 

Reason abstractly and quantitatively. 