Operations and Equations Unit of Study: More Addition & Subtraction Strategies Global Concept Guide: 2 of 3

Content Development  Provide opportunities for students use objects of equal weight and a number balance to model equations for sums and differences less than or equal to 20 using the numbers 0 to 20. Give students equations in a variety of forms that are true and false. Include equations that show the identity property, commutative property of addition, and associative property of addition. Students need not use formal terms for these properties.  13 = 13 Identity Property  = Commutative Property for Addition  = Associative Property for Addition  Common Misconception:  Many students think that the equals sign means that an operation must be performed on the numbers on the left and the result of this operation is written on the right. They think that the equal sign is like an arrow that means becomes and one number cannot be alone on the left.  Students often ignore the equal sign in equations that are written in a nontraditional way. For instance, students find the incorrect value for the unknown in the equation 9 = Δ - 5 by thinking 9 – 5 = 4.  It is important to provide equations with a single number on the left as in 18 = Showing pairs of equations such as 11 = and = 11 gives students experiences with the meaning of the equal sign as is the same as and equations with one number to the left.

Day 1  Building Conceptual Knowledge: Go Math Lesson 5.1  Students will be using bar models and snap cubes to help them solve word problems that have missing addends or subtrahends (numbers that are subtracted). As students use the models (cubes and bar models), help them understand why their model works or doesn’t work. This discussion will help them develop fundamental problem solving skills.  Ask questions such as “What do the cubes represent? How are the cubes and bar models similar? How are they different? How is you model like the problem? How is it different?”  Problem Solving/Independent Work: Go Math Lesson 5.9  p. 210 – 212  Students may use the bar models to solve these problems. Help them make the connection between the bar models and the equations.  Note – these are excellent questions for students to practice justifying their thinking and using accountable talk during discussions.

Day 2  Building Conceptual Knowledge: Voyages Excursions Lesson: Balance Me  It is important for students to clearly understand what the equal sign means. This lesson uses a pan balance to demonstrate how an equation should be “balanced” on both sides of the equal sign.  Provide opportunities for students to see the equal sign to the left of the expression as well as to the right of the expression.  Example: 7 = and = 7  During this lesson, incorporate the idea that we can check subtraction by using addition. Have students write addition equations to check their subtraction problems.

Day 3  Day 3 is a continuation of the idea of equality and that the equal sign tells us that the quantities on both sides are equivalent in value. Guide students to think of the equal sign as meaning “is the same as” or “has the same value as.”  Using a number balance allows students to see that there can be more than one addend on both sides of the equal sign.  Example: =  Problem Solving/Independent Work: Go Math Chapter 5: Lesson 5.9 Algebra – Equal or Not Equal

Enrich/Reteach/Intervention  Reteach/Intervention  Go Math Chapter 5: Add to Subtract Bingo on p. 184  Go Math Chapter 5: TE p. 185B Tier 1 and Tier 2 Interventions  Go Math Chapter 5: TE p. 217B Tier 1 and Tier 2 Interventions  True or False Equations True or False Equations  Enrich  Go Math Chapter 5: E36 Missing Numbers  Go Math Chapter 5: E42 Coach’s Choice  Go Math Chapter 5: E44 Shape Number Code

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