If-Then Moves with Integer Number Cards

Video solutions to help Grade 7 students learn how to solve equations using Algebra.

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Common Core For Grade 7

New York State Common Core Math Module 2, Grade 7, Lesson 21

Lesson 21 Student Outcomes

• Students understand that if a number sentence is true and we make any of the following changes to the number sentence, the resulting number sentence will be true:
i. Adding the same number to both sides of the equation
If a = b then a + c = b + c
ii. Subtracting the same number from both sides of the equation
If a = b then a - c = b - c
iii. Multiplying each side of the equation by the same number
If a = b then a(c) = b(c)
iv. Dividing each side of the equation by the same nonzero number
If a = b and c ≠ 0 then a ÷ c = b ÷ c
• Students revisit the integer game to justify the above referenced if-then statements.

Lesson 21 Summary

• If a number sentence is true, a = b, and you add or subtract the same number from both sides of the equation, then the resulting number sentence will be true.
• If a number sentence is true, a = b, and you multiply or divide both sides of the equation by the same number, then the resulting number sentence will be true.

NYS Math Module 2 Grade 7 Lesson 21 Exercises

Exercises 1 - 2
1. The table below shows two hands from the Integer Game and a series of changes that occurred to each hand. Part of the table is completed for you. Complete the remaining part of the table, then summarize the results.

2. Complete the table below using the multiplication property of equality.
Problem Set
3. If is divided to two of the equivalent expressions from Exercise 1, write an if-then statement using the properties of equality.