Guinea Bac Sciences Expérimentales common mistakes
Guinea Bac Sciences Expérimentales · Understand the traps and how to avoid them.
In Mathématiques, writing the final answer of a calculation (derivative, primitive, limit, probability) without stating the domain of validity or the conditions of application, e.g. deriving ln(u) or √(u) without noting u>0, or dividing by an expression that can vanish.
Candidates treat the calculation as the whole task and were trained on drills where the domain was implicit; the Guinean programme insists on 'conditions d'existence' but this is often memorised as a formula rather than applied. Under time pressure the reflex is to compute first and never return to hypotheses.
What to do instead
Adopt a fixed two-line routine before every computation: line 1 'Domaine / conditions:', line 2 the work. For each function type write the reflex condition (denominator ≠ 0, radicand ≥ 0, log argument > 0, tan argument ≠ π/2 + kπ). At the end, check the answer against the stated domain and write one sentence of conclusion. Practise on 10 mixed exercises until the reflex line appears without prompting.
In Physique, applying a formula (v = d/t, P = UI, F = ma, energy conservation) without converting units to SI and without checking dimensional homogeneity, producing answers in mixed units (g, cm, min) or numerical results off by powers of ten.
Exercises in class often use 'convenient' numbers, so the conversion step is skipped; candidates also learn formulas as strings of letters and never internalise what each symbol measures. The Guinean syllabus uses both SI and practical units, which encourages mixing.
What to do instead
Impose a three-column layout in every mechanics or electricity exercise: 'grandeur | valeur en unité donnée | valeur SI'. Convert on the middle line before substituting. After computing, perform a quick dimensional check (e.g. m/s for speed, N for force, J for energy) and a plausibility check (a car does not travel at 300 m/s). Train with deliberately 'trap' data in g, cm and minutes.
In Chimie, writing and balancing equations carelessly: forgetting diatomic molecules (O2, H2, Cl2, N2), omitting state symbols, or balancing atoms while ignoring charge balance in ionic half-equations, then carrying the error into the stoichiometric calculation.
Balancing is seen as a formality before 'the real problem'; candidates memorise a few equations and try to reproduce them rather than applying conservation of elements and charge. Ionic media (oxidation-reduction, acid-base) are the least practised.
What to do instead
Use an explicit checklist written at the top of the answer sheet: (1) correct formulas of reactants and products, (2) balance elements other than O and H, (3) balance O with H2O, (4) balance H with H+, (5) balance charge with electrons, (6) add state symbols. Recopy the balanced equation on its own line before any mole calculation, and verify atom counts on both sides in the margin.
In Sciences de la Vie et de la Terre, answering a document-based question with general knowledge instead of extracting the data: describing 'photosynthesis produces oxygen' when the question asks to interpret a measured curve of O2 versus light intensity, and never quoting the numerical values or units shown.
Candidates revise definitions and diagrams but rarely practise the 'exploiter un document' competency; they believe a correct-sounding sentence earns marks. Reading a graph and linking it to a mechanism is a distinct skill that is under-drilled.
What to do instead
Follow a written protocol for every document: (1) identify the axes/legend and units, (2) cite two precise readings with numbers, (3) state the relationship observed in one sentence, (4) link it to a course mechanism, (5) conclude. Practise on past graph, table and experiment questions, always writing the numbers. Train yourself to refuse any sentence that contains no data from the document.
In Français, producing a dissertation or commentaire composé with no explicit plan: a long paraphrase of the text or a list of general ideas, no problématique, no transitions, and quotations copied without analysis or line references.
The exercise is often learned by imitation of model essays rather than by method; candidates fear an empty page and write immediately. The Guinean programme gives heavy weight to the 'introduction, développement, conclusion' structure but candidates do not rehearse the 10-minute planning phase.
What to do instead
Force a 10–15 minute plan written on a separate sheet: problématique, two or three parts with two sub-arguments each, and the quotation or example attached to each. In the commentaire, use the formula 'citation + procédé + effet/interprétation'. Write the transitions last, as full sentences. Rehearse full timed essays (4h) at least twice before the exam, self-marking against a written grid.
In Anglais, writing a free composition or answering comprehension questions in long, over-ambitious sentences with French word order and calques ('I have 18 years', 'explain me', 'actually' for 'currently'), producing errors that break communication.
Candidates try to display complex grammar they do not control, and transfer French structures directly. Classroom practice often focuses on grammar drills rather than controlled production, so the risk is taken for the first time in the exam.
What to do instead
Apply a 'simple and correct' rule: short sentences, subject-verb-object, one tense per sentence. Memorise a personal list of the 20 most frequent French calques with their English equivalents. For comprehension, answer in your own words with a short quoted phrase as evidence. Re-read once only to check third-person -s, plurals, and prepositions of time.
In Histoire-Géographie, narrating events without dates, actors or spatial reference, or producing a 'carte' or 'croquis' with no title, no legend and no scale; answers drift into general opinion rather than organised historical or geographical argument.
The subject is often revised as stories to remember, not as structured answers; map conventions are treated as decoration. Candidates also confuse the two disciplines' methods and answer a geography question with a history narrative.
What to do instead
For each major topic, memorise a minimal fact sheet: 5 dates, 5 actors, 5 key concepts, 1 map reference. For map work, impose the rule 'titre – légende organisée – échelle – orientation' before drawing anything. For essays, use the chronology/scale framework explicitly (e.g. local–national–global) and open each paragraph with a dated or located statement.
In Éducation Civique et Morale, giving abstract moralising answers ('il faut être sage', 'la citoyenneté est importante') without naming the relevant institution, right, duty or legal text, and without applying it to the concrete situation described in the question.
The subject is perceived as 'easy points' requiring only good sentiments, so it is revised last and superficially. Candidates do not know the institutional vocabulary (commune, préfecture, constitution, droits et devoirs) well enough to use it precisely.
What to do instead
Build a vocabulary sheet per theme: institution, text of reference, right, corresponding duty, example of a real situation in Guinea. In answers, always use the pattern 'situation → principle/rule → institution responsible → consequence'. Practise by taking a concrete case (e.g. a dispute in a neighbourhood) and writing a 10-line structured response using that pattern.
In Philosophie, treating the dissertation as personal opinion or as a summary of a doctrine: no analysis of the terms of the subject, no problem, no argumentative progression, and references dropped as names without explaining what they contribute.
The subject feels inaccessible and candidates fall back on 'je pense que', or on reciting a course chapter. The distinction between opinion and philosophical argument is rarely made explicit in revision, and the planning stage is skipped.
What to do instead
Start every essay by defining the key terms and formulating the tension in the subject as a question ('d'un côté… de l'autre…'). Then build a three-part progression: thesis, objection, resolution. For each reference, write one sentence explaining the idea and one sentence linking it to the argument. Rehearse with 20-minute plans only, checked against a model structure, before writing full essays.
In Éducation Physique et Sportive, neglecting the theoretical component (règles, secourisme, physiologie de l'effort, hygiène) and, in practical evaluation, mismanaging effort: sprinting at the start of an endurance test, ignoring the warm-up, or failing to respect safety and officiating rules.
Candidates assume EPS marks come only from natural athletic ability and skip the written paper and the rules; pacing and warm-up are not practised as examinable skills. Officiating and safety rules are often learned once and forgotten.
What to do instead
Treat the theoretical paper as a normal subject: revise the rules of the evaluated activities, basic first aid (protection, alert, rescue) and effort physiology from a one-page summary per theme. In training, rehearse the evaluated protocol exactly: standardised warm-up, measured pacing (negative split), and one session officiating and refereeing so the rules are applied, not just read.