Botswana BGCSE Science Double Award (0569) common mistakes
Botswana BGCSE Science Double Award (0569) · Understand the traps and how to avoid them.
When asked to explain diffusion or osmosis, the candidate writes only a definition ("movement of particles from high to low concentration") and never names the particles, the membrane, or the direction of net water movement in the specific situation described in the question.
Definitions are memorised as a single sentence and reproduced verbatim; candidates do not realise that mark schemes award points for applying the idea to the given case (e.g. water leaves the vacuole, so the cell becomes flaccid), not for the definition alone.
What to do instead
Practise a three-part answer frame for every transport question: (1) what moves, (2) from where to where, (3) the consequence for the cell or organism. Write the frame out for five different contexts (root hair cell, gut villus, leaf stoma, potato strip in salt solution, red blood cell in pure water) until the pattern is automatic.
On questions about the heart, blood vessels or the alimentary canal, the candidate labels structures correctly but cannot state the function or the link between structure and function, so answers such as "the villus has a large surface area" are left unconnected to absorption.
Revision has focused on naming parts of diagrams rather than on the explanatory chain (feature to function to benefit to organism). Examination wording such as "explain how" is read as "state what", so the candidate stops after one factual point.
What to do instead
For each structure, build a two-column table: feature and advantage. Then rehearse turning each row into a full sentence using "because", "so that" and "this means". Answer every "explain" question with at least two linked points, each joined by a causal connective.
In ecology and conservation questions, the candidate describes what happens to a population ("the number of fish went down") without stating the cause, the effect on other organisms, or suggesting a management measure, and confuses terms such as habitat, community, population and ecosystem.
Everyday language is used instead of ecological terminology, and candidates treat food chains as lists of names rather than as flows of energy and matter, so they cannot predict knock-on effects.
What to do instead
Learn the four definitions with a worked example from one local ecosystem, then practise chain reasoning: change in A leads to change in B leads to change in C. For every conservation question, add one named measure (quota, protected area, breeding programme) and one reason it works.
When writing formulae and balancing equations, the candidate changes subscripts to make an equation balance (writing H2O as H2O2 or FeO as Fe2O3) or omits state symbols and charges in ionic equations.
Balancing is treated as a counting puzzle rather than as conservation of atoms, and the difference between a subscript inside a formula and a coefficient in front of it has not been secured.
What to do instead
Adopt a strict routine: write the correct formulae first from valency, count atoms on each side in a table, and adjust only the large numbers in front. Check by recounting. Do ten equations where the correct answer needs a coefficient of 2 or 3, and mark any subscript you changed as an error.
On acids, bases and salts questions, the candidate names the salt produced but cannot write the word or symbol equation for the reaction, cannot choose the right acid for a named salt, and describes a test for a gas without stating the observation.
The topic is learned as a list of reactions rather than as a pattern (acid plus base, acid plus carbonate, acid plus metal), and practical observations are separated in the candidate's mind from written chemistry.
What to do instead
Build a reaction grid: acid down the side, base/carbonate/metal across the top, with the salt rule (hydrochloric gives chlorides, sulfuric gives sulfates, nitric gives nitrates) and the gas in each cell. For each gas, write observation plus test (limewater turns milky, lighted splint pops, damp litmus bleaches).
In extraction and industrial-process questions, the candidate describes the blast furnace or electrolysis as a single step and cannot explain why a reducing agent, a high temperature or a particular electrolyte is needed, nor why a metal is extracted by electrolysis rather than by carbon.
The process is memorised as a narrative sequence of raw materials without the underlying principle (reactivity series and electron transfer), so the candidate cannot answer "why" questions.
What to do instead
Anchor each process to the reactivity series: metals above carbon need electrolysis, metals below carbon can be reduced by carbon. For each named process, write three lines: input, key condition, reason for that condition. Practise explaining one process to a partner without notes.
In force and motion calculations, the candidate substitutes numbers into an equation without converting units, mixes up mass and weight, and treats speed, velocity and acceleration as interchangeable; answers are given without units or with the wrong unit.
Formulae are recalled as symbols without the associated units, and candidates rush to calculate before listing the given quantities, so a distance in centimetres is inserted where metres are required.
What to do instead
Use a fixed layout: list given values with units, convert to SI, write the equation, substitute, then state the answer with its unit and a reasonableness check. Drill conversions (cm to m, g to kg, minutes to seconds) separately from the physics until they are automatic.
In ray diagrams and wave questions, the candidate draws rays without arrows, uses a ruler-free sketch where the normal or principal axis is missing, and confuses frequency with wavelength or amplitude when explaining pitch and loudness.
Diagrams are treated as decoration rather than as a marked part of the answer, and the wave equation is applied by rote without linking each quantity to an observable property of the sound or light.
What to do instead
Practise a checklist for every diagram: principal axis, normal at the point of incidence, arrows showing direction, labels. For waves, make a three-row table linking amplitude to loudness or brightness, frequency to pitch or colour, and use v = f times wavelength with units checked.
In circuit questions, the candidate misidentifies series and parallel arrangements, adds resistance values in the wrong way, and cannot explain the effect of adding a component on current or potential difference; ammeter and voltmeter placement is drawn incorrectly.
Circuit rules are memorised as statements without a mental model of charge flow, and candidates do not check their answer against the rule that current is conserved at a junction and potential differences in series add to the supply.
What to do instead
Draw circuits by hand and annotate them with current values at each point and potential difference across each component. Learn two checks: current in series is the same everywhere, potential differences in series sum to the supply. Practise five circuits where one value is unknown and verify with the checks.
In practical and data-handling questions, the candidate plots points without a line of best fit, joins points dot to dot, omits units and axes labels, reads a gradient from a single pair of points instead of the line, and describes an anomaly as "a mistake" rather than identifying it and explaining how to reduce it.
Graph work is seen as presentation rather than as a tool for finding a relationship, and candidates have not been taught to distinguish random error from systematic error or to state a control variable explicitly.
What to do instead
Follow a graph checklist every time: labelled axes with units, even scale, plotted points, smooth line of best fit, large triangle for gradient with values shown. For investigations, write the variables table (independent, dependent, two controlled) before writing the method, and practise describing one improvement that would reduce each type of error.