Education Technology

Expressions and Equations / Linear Inequalities in One Variable

Grade Level 6,7
Activity 8 of 18
In this lesson students focus on inequalities and methods of solving them, building on the concept of solution- and order-preserving moves in the context of an inequality.

Planning and Resources

Students should be able to identify order-preserving moves while solving inequalities in one variable and justify the solution for a linear inequality in one variable.

solution-preserving moves

Standard: Search Standards Alignment


Lesson Snapshot


Students develop a sense of “order- and solution-preserving” moves that can be applied to inequalities and how these moves relate to the solution set for an inequality.

What to look for

Students will encounter the fact that multiplying both sides of an inequality by a negative number does not preserve order.

Sample Assessment

What are all the possible whole numbers that make 8-___>3 true?

a. 0, 1, 2, 3, 4, 5
b. 0, 1, 2, 3, 4
c. 0, 1, 2
d. 5

Answer: b

The Big Idea

Finding the solution to an inequality in one variable involves four ideas:
1. The smaller of two number is to the left of the larger;
2. if one number is less than another, \(a < b\), then some positive \(c\) added to \(a\) will equal \(b\) \((a+c = b)\);
3. the point of equality (boundary point) divides a set of values into those greater than and those less than that point; and
4. some operations on both sides of an inequality preserve order and some do not (in particular, multiplying or dividing by a non-zero number).

What are the students doing?

Students reason about order-preserving and solution- preserving moves while using interactive visuals on a number line.

What is the teacher doing?

Encourage students to think about the ways they learned to solve equations that apply similarly to solving inequalities.