Graphing Linear Inequalities in Two Variables
I can graph a linear inequality in two variables and shade the correct side of the boundary.
What students learn
Students learn to graph the boundary line of a two-variable inequality, solid or dashed, and shade the side a test point shows is true, getting y alone first.
See inside
The key rule
Graph the boundary: solid for ≤ or ≥, dashed for < or >. Test a point off the line: if it is true, shade its side; if it is false, shade the other side.
y ≤ x − 1 → solid y = x − 1
(0, 0) is the easiest point to test, unless the line passes through it.
Watch out
Graph 2x − y > 4. Which side is shaded?
The mistake: > means shade above the lineThat rule only works once y is alone.
The fix: −y > −2x + 4, so y < 2x − 4: shade belowDividing by −1 reverses it. Test (0, 0): 0 > 4 is false.
The mistakes it targets
- Shades by the symbol before y is alone
- Keeps the symbol after dividing by a negative
- Mixes up solid and dashed boundary lines
- Counts a point on a dashed line as a solution
- Uses a test point that lies on the boundary line
The interactive Teacher Deck (32 slides, PowerPoint)
- The Learn page taught on screen: 8 fill-in blanks, each filled on its own click as students write it
- The worked example one slide per step (four steps), each with the reason for the step
- Six practice and three apply problems: a your-turn slide with a think-time bar, then the solution one line per click
- Jump buttons on every slide: go straight to any problem, the answer bank or the exit ticket
- Speaker notes on each problem: the question to ask, the worked answer and the common error to listen for
- A completed deck PDF (19 pages) with every slide fully built, to print or post
The student packet (9 pages)
- Learn: guided notes with four definitions, the key rule, a worked example and a Watch Out error pair
- Practice: two warm-up, two standard and two stretch problems, with an answer bank for self-checking that hides three common-mistake decoys
- Apply: one word problem, a reasoning prompt and one error analysis
- Assess: an exit ticket of four items, two per page, with an I-can self-rating
- Homework (page 5): eight new problems, two warm-up, four standard and two stretch
- Answer key (pages 6–7): every problem worked step by step, four common mistakes with what to do about each, and a grading guide, plus the homework key (page 8)
- Color and ink-saver editions of the whole packet
Standard codes refer to the Common Core State Standards for Mathematics. Math Class 678 is an independent publisher, not affiliated with, sponsored by, or endorsed by NGA Center or CCSSO. Every product is sold on Teachers Pay Teachers.