MYP · Mathematics (Extended) MYP Year 5
Functions
38 min readAdvancedCore strand — recurs across nearly every criterion (A, B, C) in MYP5 Extended assessment; the single most heavily tested chapter of the year
Every 'model this real situation' question in your MYP5 exam is secretly asking one thing: can you treat a rule as a function, evaluate it, graph it, and pull information back out of it? That's this entire chapter. Get comfortable moving between a table of values, an equation and a graph — examiners test all three representations of the same function inside a single question, and most lost marks come from language and set-up, not algebra.
Overview — the shape of this chapter
Why this topic is basically the whole course
A function is a reliable machine: put a number in, get exactly one number out. Every other idea here — domain, range, transformations, inverses, composites — is just asking what the machine accepts, what it produces, and what happens when you chain machines together or run one backwards.
- MYP5 Extended blends algebraic fluency (solving, simplifying) with the language of functions (notation, domain, range) — most marks are lost on wording, not working.
- Real-world contexts (cost plans, drone flights, bridge deflection) dominate the exam bank — you build a function FROM a table or story, not just manipulate one you're given.
- Graphs, tables and equations are three views of the same object — a question can switch representation mid-way and still expects the same reasoning underneath.
The shape of the chapter
Command terms that decide how you answer
| Command term | What it demands | AO | Mark-earning move |
|---|---|---|---|
| State | Give a brief answer — a definition, value or equation — with no explanation. | AO1 | 1 mark per correct fact; a vague or partial version scores nothing. |
| Evaluate | Substitute the given input into the function and simplify to a single numerical answer. | AO2 | Showing the substitution earns a method mark even if final arithmetic slips. |
| Determine / Deduce | Use given information (a graph, table or point) to establish something not stated outright — reasoning must be visible. | AO2/AO3 | The answer alone rarely scores full marks — the mark scheme wants the calculation or comparison behind it. |
| Justify | Give a reason, backed by a calculation or a stated rule (e.g. the vertical line test), for why a claim is true or false. | AO3 | A correct answer with no reason attached still scores 0. |
| Construct | Build an equation, table, graph or system directly from context, points or a description. | AO2 | Marks are awarded for each construction step (e.g. each equation in a system), not just the final result. |
| Solve | Find the value(s) of the unknown satisfying an equation or inequality. | AO2 | All valid solutions must be listed — dropping one root of a quadratic costs a mark even with perfect method. |
Key point
A relation is a function only when every input gives EXACTLY one output. Graph test: no vertical line crosses the curve more than once. Table/mapping test: no input value repeats with a different output.
Overview