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Lessons
Comparing Connecting Cubes 4: Balancing
Discipline
Mathematics
Grades
Kindergarten, 1, 2
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Professional Commentary

This lesson features two activities using connecting cubes on a pan balance to model subtraction. Students may also enjoy the pan balance applet linked to the site. The resource includes a list of children's counting stories, recording sheets, discussion questions, suggestions for assessment, and questions for teacher reflection. (sw)


Common Core State Standards for Mathematics
Kindergarten
Operations and Algebraic Thinking
Understand addition as putting together and adding to, and understand subtraction as taking apart and taking from.
K.OA.A.1 
Represent addition and subtraction with objects, fingers, mental images, drawings, sounds (e.g., claps), acting out situations, verbal explanations, expressions, or equations.
K.OA.A.2 
Solve addition and subtraction word problems, and add and subtract within 10, e.g., by using objects or drawings to represent the problem.
Grade 1
Operations and Algebraic Thinking
Represent and solve problems involving addition and subtraction.
1.OA.A.1 
Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.
Add and subtract within 20.
1.OA.C.6 
Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
Work with addition and subtraction equations.
1.OA.D.7 
Understand the meaning of the equal sign, and determine if equations involving addition and subtraction are true or false. For example, which of the following equations are true and which are false? 6 = 6, 7 = 8 – 1, 5 + 2 = 2 + 5, 4 + 1 = 5 + 2.
Grade 2
Operations and Algebraic Thinking
Represent and solve problems involving addition and subtraction.
2.OA.A.1 
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.
2.OA.B.2 
Fluently add and subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.
Ohio Mathematics Academic Content Standards (2001)
Number, Number Sense and Operations Standard
Benchmarks (K–2)
H.
Model, represent and explain subtraction as comparison, take-away and part-to-whole.
Grade Level Indicators (Grade Kindergarten)
10.
Model and represent addition as combining sets and counting on, and subtraction as take-away and comparison. For example:
a. Combine and separate small sets of objects in contextual situations; e.g., add or subtract one, two, or another small amount.
b. Count on (forward) and count back(backward) on a number line between 0 and 10.
Grade Level Indicators (Grade 1)
11.
Model, represent and explain subtraction as take-away and comparison. For example: a. Model and explain subtraction using physical materials in contextual situations. b. Draw pictures to model subtraction. c. Write number sentences to represent subtraction. d. Explain that subtraction of whole numbers yields an answer smaller than the original number.
12.
Use conventional symbols to represent the operations of addition and subtraction.
Grade Level Indicators (Grade 2)
6.
Model, represent and explain subtraction as comparison, take-away and part-to-whole; e.g., solve missing addend problems by counting up or subtracting, such as "I had six baseball cards, my sister gave me more, and I now have ten. How many did she give me?" can be represented as 6 + ? = 10 or 10 - 6 = ?.
Principles and Standards for School Mathematics
Number and Operations Standard
Understand meanings of operations and how they relate to one another
Expectations (Pre-K–2)
understand various meanings of addition and subtraction of whole numbers and the relationship between the two operations;