MYP Maths Inequalities: Assessment, Solving & Common Mistakes

Inequalities in MYP 4-5 aren't tested as a stand-alone topic — they're assessed through the same four criteria as everything else, mostly Criterion A (Knowing and Understanding) for solving technique and Criterion D (Applying Mathematics in Real-Life Contexts) when the inequality models a real constraint like a budget or weight limit.

An inequality compares two expressions using <, >, ≤ or ≥ instead of an equals sign, so instead of one exact answer you get a whole range of values that work. In MYP 4-5 you'll meet linear inequalities, compound inequalities, and their graphical representations on number lines and coordinate axes.

Inequalities most often sit under Criterion A (Knowing and Understanding) for solving procedures, and Criterion D (Applying Mathematics in Real-Life Contexts) whenever a problem models a genuine constraint — a delivery van's weight limit, a fixed budget, a minimum test score. Criterion B (Investigating Patterns) can appear if a task asks you to generalise a system.

You solve a linear inequality exactly like an equation — add, subtract, multiply or divide both sides to isolate the variable — with one crucial exception: multiplying or dividing by a negative number flips the inequality sign. Skip that step and your algebra is correct but your final answer is backwards.

An equation like 2x + 3 = 9 has exactly one solution — x = 3. An inequality like 2x + 3 > 9 has infinitely many solutions, written x > 3, shown as a ray on a number line. The algebra is almost identical; the only extra rule is flipping the sign when you divide by a negative.

A compound inequality sandwiches a variable between two bounds, like −3 < 2x + 1 ≤ 7, and you solve it by performing the same operation on all three parts simultaneously rather than splitting it into two separate inequalities. This keeps the solution as one connected interval instead of two disconnected pieces.

On a number line, an open circle marks a value excluded by < or >, and a filled circle marks a value included by ≤ or ≥, with an arrow showing which direction the solution extends. On a coordinate plane, a dashed boundary line means strict inequality and a solid line means ≤ or ≥, with the solution region shaded.

The mistake I mark down most often on Criterion A work is forgetting to flip the inequality sign when dividing by a negative — it turns an otherwise perfect method into a wrong final answer. Second most common: mixing up open and closed circles on a graph, which costs marks under Criterion C for clear communication.

A level 7-8 on Criterion A means accurate, efficient solving with no sign errors and correct notation throughout — inequality or interval notation used consistently. For Criterion D, top marks mean interpreting the solution back in its real context, not leaving it as bare algebra: state what x ≤ 12 actually means for the problem.

Yes — for schools using the IB's optional MYP eAssessment, the on-screen Mathematics paper at Year 5 includes inequality questions testing both algebraic solving and graphical interpretation. Most schools, though, assess inequalities through internally set unit tasks marked against the criteria rather than through the eAssessment route.

Everything you learn solving linear inequalities in MYP 4-5 becomes the toolkit for two different DP directions. Maths AA extends inequalities into quadratics and absolute-value problems for curve sketching, while Maths AI leans on inequalities for linear programming — optimising cost or profit subject to real constraints in the AI SL/HL toolkit.

Inequalities are generally one of the more approachable MYP 4-5 topics because the algebra mirrors equation-solving so closely — most of the difficulty is procedural rather than conceptual. Where marks slip is the negative-sign-flip rule and imprecise graph notation, not a genuine gap in understanding, so careful checking usually lifts a grade more than extra practice hours alone.

Look for MYP-specific practice with full worked solutions, not a generic textbook chapter, so your child can see exactly where sign errors creep in and how criterion-style questions are marked. Topical worksheets and revision notes covering inequalities, paired with a mark scheme for self-checking, work well alongside classroom teaching.