QCAA Engineering EA common mistakes
QCAA Engineering EA · Understand the traps and how to avoid them.
When asked to justify a design decision or evaluate a solution, the candidate describes what they built or what the process was, without stating criteria, comparing alternatives, or reaching a judgement.
The candidate treats 'explain' and 'evaluate' as the same command word and writes a chronological narrative of their project, because that is the material they know best and it feels safe to describe rather than judge.
What to do instead
Before writing, underline the command word and write a one-line plan naming the criteria (function, cost, safety, sustainability), the alternatives considered, and the verdict. Check the finished answer contains an explicit judgement sentence such as 'Option B is preferred because...'. Practise rewriting past narrative answers into criterion-by-criterion comparisons.
The candidate selects a material by name or by a single headline figure (for example 'aluminium because it is light') without citing the specific property, its units, and how it matches the service conditions.
Material selection is often taught as a list of materials with adjectives attached, so the candidate recalls labels rather than property data and never links selection to the loads, environment, or manufacturing route in the scenario.
What to do instead
Use a property-matching table: list the functional requirements, convert each to a measurable property with units (density in kg/m^3, yield strength in MPa, thermal conductivity in W/(m.K)), then justify each material against those numbers. Always name the trade-off being accepted, such as lower strength for reduced mass.
In free-body diagrams and equilibrium calculations, the candidate omits a reaction, draws a force at the wrong point or direction, or resolves components with sine and cosine swapped relative to the stated angle.
Candidates sketch the diagram quickly from memory of a similar problem rather than from the actual supports in the question, and they apply sine and cosine by rote without checking which side is opposite the given angle.
What to do instead
Adopt a fixed routine: isolate the body, mark every contact and support, draw reactions in assumed positive directions, then resolve with an angle measured from a named axis and verify with a limiting case (angle 0 or 90 degrees). Check that the number of unknown reactions matches the support type before solving.
The candidate substitutes numbers into a kinematics or energy equation without converting to SI base units, or mixes scalar energy methods with vector force methods in the same line of working.
Exam questions deliberately use grams, millimetres, kilometres per hour, or kilojoules, and candidates work in the units given because conversion feels like an optional extra step under time pressure.
What to do instead
Write a conversion line at the top of every calculation (for example mass in kg, length in m, speed in m/s) and carry units through the working so the final unit is derived, not asserted. Keep energy and momentum approaches in separate blocks and state which principle is being applied before substituting.
On orthographic and sectional drawing tasks, the candidate omits hidden detail, misplaces a view in third-angle projection, or leaves out dimensions and a title block, producing a drawing that is internally consistent but not to standard.
Candidates focus on making the shape look right and treat projection layout, line types, and dimensioning conventions as cosmetic, often because they have practised only free sketching rather than standard drawing sets.
What to do instead
Work to a checklist in fixed order: view layout for the stated projection, visible and hidden line types, centrelines, dimensions with units and no duplication, then title block and scale. Redraw one full standard drawing set per week and mark it against the checklist before checking the shape.
In CAD and technical communication answers, the candidate names a tool or file format but cannot explain what it is used for, or produces a report or drawing with no audience-appropriate structure, labels, or units.
Software skills are learned by clicking through menus, so knowledge is procedural and hard to verbalise; report writing is often treated as an afterthought appended to the technical work rather than planned for a reader.
What to do instead
For each CAD feature or format, write a one-sentence purpose statement and a worked example of when it is preferred. For communication tasks, plan the document as audience, purpose, structure, then content, and include a labelled figure or table with units and a caption in every answer.
Project management answers list tools such as Gantt charts or risk matrices without applying them to the scenario, or the candidate presents a schedule with no dependencies, no critical path, and no contingency.
Candidates memorise tool names as definitions and do not practise constructing a small schedule or risk register from a described project, so they cannot show how the tool changes decisions.
What to do instead
Practise building a five-to-eight task schedule from a scenario, identifying predecessors, the critical path, and float, then state what happens if a critical task slips. Do the same for a short risk register with likelihood, consequence, and a specific mitigation action.
Sustainability, ethics, and safety questions are answered with generic statements such as 'it is good for the environment' or 'safety is important', with no lifecycle stage, stakeholder, standard, or control identified.
These topics are perceived as opinion-based, so candidates write vague value statements instead of using the analytical frameworks (lifecycle stages, hierarchy of controls, stakeholder analysis) that the syllabus expects.
What to do instead
Anchor every response to a named framework: for sustainability, walk material extraction, manufacture, use, and end-of-life; for safety, apply the hierarchy of controls from elimination down to PPE; for ethics, name the affected stakeholders and the competing obligations. Support each claim with a specific consequence or control.
The candidate answers only the first part of a multi-part question, or writes a long response to a low-mark part and runs out of time for the high-mark evaluation question.
Candidates read the stem and start writing immediately, and they allocate effort by interest or by the order questions appear rather than by mark value, so the highest-value reasoning is left unfinished.
What to do instead
Before writing, scan the whole paper and note the mark allocation against each part, then budget minutes roughly in proportion. In the answer, number each sub-part and write a separate short paragraph for each, checking off the command word and mark value before moving on.
Numerical answers are given without units, with excessive or insufficient significant figures, or with no statement of whether the result is physically sensible.
Candidates treat the number as the answer and the unit as decoration, and they do not build the habit of a plausibility check, so unit and magnitude errors pass unnoticed even when the method is correct.
What to do instead
End every calculation with a sentence giving the value, the unit, and a sanity check against an expected order of magnitude (for example a beam deflection of 3 m is not credible). Match significant figures to the precision of the given data and state assumptions explicitly.