Guinea CEE common mistakes
Guinea CEE · Understand the traps and how to avoid them.
In a calculation, working only with numbers and dropping units until the final line, so a speed given in km/h is substituted into a formula that needs m/s without conversion.
Guinean secondary teaching often emphasises the numerical result and the formula, so candidates memorise the expression and rush to substitute, treating units as decoration rather than part of the quantity.
What to do instead
Write the unit beside every substituted value and perform an explicit conversion line (e.g. 72 km/h = 72 × 1000/3600 = 20 m/s) before calculating; finish by checking that the unit of the answer matches the quantity asked for.
In a geometry or trigonometry problem, drawing a freehand sketch, assuming the triangle is right-angled or the figure is to scale, and reading lengths or angles off the sketch instead of proving them.
Under time pressure the sketch becomes the proof; candidates confuse a diagram that illustrates a statement with a diagram that establishes it, a habit reinforced by exercises where the figure is already drawn.
What to do instead
Redraw the figure with the given data labelled, mark only what is stated or proven, and write a short chain: given → property used (Pythagoras, angle sum, similarity) → conclusion. Treat any right angle or equality not stated in the text as something to prove, not to use.
Solving an equation by dividing both sides by an expression containing the unknown (for example dividing by x or by x−2) and thereby losing one or more solutions.
The reflex is to 'simplify' as in arithmetic; candidates do not yet treat division by a possibly zero quantity as an operation requiring a condition.
What to do instead
Factor instead of dividing: bring everything to one side, factor, and apply the zero-product rule. If division is unavoidable, state the condition (denominator ≠ 0) and check the discarded case separately at the end.
In mechanics, applying F = ma to a system without drawing the forces, omitting weight, normal reaction or friction, or mixing the forces on different bodies.
Candidates memorise the formula and look for numbers to plug in; the free-body diagram is seen as optional decoration rather than the step that determines the equation.
What to do instead
Always draw a separate free-body diagram per body, choose axes, list every force with its direction, then project onto the axes. Check each force is exerted by a named object on a named object, and never include a force and its reaction in the same diagram.
Confusing mass and weight, or confusing a scalar and a vector quantity (speed vs velocity, distance vs displacement), and giving a vector answer without direction.
Everyday French usage ('il pèse 60 kilos') blurs the distinction, and the syllabus introduces vectors early while numerical drills rarely penalise a missing direction.
What to do instead
Keep a personal table of quantity / symbol / unit / scalar or vector, and in every answer state magnitude with unit and, for vectors, the direction or sign convention used. Convert weight problems explicitly with P = mg and g ≈ 9.8 N/kg (or 10 N/kg as instructed).
Balancing a chemical equation by changing subscripts inside formulas (writing H2O2 as H2O to make the count work) instead of adjusting coefficients.
The candidate treats the equation as an arithmetic puzzle to be made to balance, forgetting that a formula encodes a fixed composition and that changing it changes the substance.
What to do instead
Write formulas first and freeze them; balance only with coefficients, starting from the most complex species, and finish with a check of each element and of charge. Practise by taking an unbalanced equation and listing atom counts in a table before writing any coefficient.
Describing a solution as 'acidic' or 'basic' from the colour of an indicator alone, or writing pH values without linking them to concentration, and confusing pH decrease with acidity decrease.
Indicator colours are memorable and visually satisfying, while the logarithmic relation pH = −log[H3O+] is abstract; candidates therefore substitute colour for measurement.
What to do instead
State both the observation and the interpretation ('turns red with helianthine, so pH < 3.1'), and always attach a numerical scale reminder: lower pH = more H3O+ = more acidic. Work a few conversions both ways (10^-3 mol/L ↔ pH 3) until the direction is automatic.
In genetics, writing a cross without defining the alleles and genotypes first, then confusing genotype ratios with phenotype ratios or forgetting that a recessive phenotype requires two recessive alleles.
The vocabulary (dominant, recessive, homozygous) is learned as labels rather than as rules for constructing a cross, so the Punnett square is filled mechanically.
What to do instead
Begin every genetics answer with an explicit key (A = dominant allele, a = recessive), give parental genotypes, then the gametes, then the square, and state genotype and phenotype ratios as separate lines. Test the logic by asking whether the stated phenotypes are compatible with the genotypes.
In a French writing task, producing a long narration with no plan, drifting between tenses (passé composé and imparfait mixed at random), and ignoring the required text type (letter, article, dialogue).
Candidates equate length with marks and write as they think, without the pre-writing stage that the composition exercise rewards; tense contrast between background and event is rarely automated.
What to do instead
Spend five minutes on a plan: text type, addressee, purpose, two or three parts, and the tense each part needs. Draft with a clear rule - imparfait for description and habitual background, passé composé for completed events - then reread specifically for tense consistency, agreement and connectors.
In the English paper, translating word for word from French, answering a reading-comprehension question by copying a whole paragraph, or writing a composition that does not address the prompt.
Limited active vocabulary pushes candidates towards literal translation and towards copying the text as a safe answer; the comprehension questions reward reformulation, which is not practised.
What to do instead
For comprehension, locate the relevant sentence, then answer in one short sentence of your own using the question's words. For the composition, underline the task words (describe, give your opinion, write a letter to…) and produce a short plan with one idea per paragraph; keep sentences short and grammatically controlled rather than ambitious.