Fukui Entrance Science common mistakes
Fukui Entrance Science · Understand the traps and how to avoid them.
When a problem gives a distance–time graph or a speed–time graph, the candidate reads the height of the curve as speed in both cases, so on a distance–time graph they treat a steep straight segment as 'accelerating' instead of constant speed.
The two graph types look identical in layout, and candidates memorise 'slope = something' without fixing which quantity is on which axis. Under time pressure they default to the more familiar idea that a rising line means speeding up.
What to do instead
Before reading any value, write on the paper 'vertical axis = ___'. Then apply the fixed rule: on a distance–time graph the gradient is speed and a straight line means constant speed; on a speed–time graph the gradient is acceleration and the area under the line is distance travelled. Practise by sketching both graphs for the same journey (walk, stop, run) and comparing them side by side.
The candidate computes work as force × distance even when the force is perpendicular to the motion (for example carrying a bag horizontally while gravity acts downward), and concludes that gravity does work on the bag.
The formula W = Fd is remembered without the condition that the force must have a component along the displacement. The word 'force' and the word 'distance' both appear in the problem, so the candidate multiplies them.
What to do instead
Always resolve the force into a component along the displacement first: W = F d cos θ, and note that a force at 90° to the motion does zero work. Test understanding with three cases: pushing a box along the floor (work done), carrying it horizontally (gravity does no work), and lowering it slowly (gravity does positive work, the hand does negative work).
In a circuit with two resistors, the candidate assumes the current is the same through parallel branches, or assumes the voltage is the same across series resistors, then gets every subsequent value wrong.
Series and parallel rules are learned as two lists of formulas that get mixed up. Candidates also carry over the intuition that 'the battery voltage is used up a bit at each component' into parallel branches.
What to do instead
Anchor on two physical statements rather than formula lists: in a series loop there is only one path, so the current is identical everywhere and the voltages add to the supply; in a parallel network each branch is connected directly across the same two points, so the voltages are equal and the branch currents add. Redraw every circuit as a single loop or a set of independent loops before calculating, and check the totals with Ohm's law.
The candidate draws the magnetic field around a straight current-carrying wire as lines radiating outward from the wire like an electric field, or reverses the direction of the field when the current direction is reversed but keeps the same sense.
Electric field patterns (radial lines from a point charge) are studied first and dominate the mental image. The right-hand rule is memorised as a gesture without linking thumb to current and fingers to field direction.
What to do instead
Draw the field as concentric circles in a plane perpendicular to the wire, with the wire shown as a dot (current out of the page) or a cross (current into the page). Apply the right-hand grip rule explicitly each time: thumb along the conventional current, curled fingers give the field direction. Practise reversing the current and redrawing the arrows.
The candidate treats a sound or light wave as if changing its frequency changes its speed in the same medium, and states that a higher-pitched sound travels faster through air.
The everyday experience that 'more energy means faster' is applied to waves, and the formula v = f λ is used without the constraint that v is set by the medium.
What to do instead
State the rule before calculating: in a given medium the wave speed is fixed by the medium, so a change in frequency changes the wavelength inversely (v = f λ with v constant). Compare cases explicitly: sound in air versus sound in water (speed changes with medium), and a high note versus a low note in the same air (speed identical, wavelength differs).
When asked to separate a mixture, the candidate chooses filtration for a dissolved salt in water, or evaporation for a mixture of two liquids, instead of matching the method to whether the components are solid–liquid, dissolved, or mutually soluble liquids.
The methods are memorised as a list (filtration, evaporation, distillation, chromatography) without a decision rule, so the most recently revised method is applied regardless of the mixture type.
What to do instead
Use a two-question decision tree: (1) Is anything dissolved? If not, filtration separates an insoluble solid. (2) If dissolved, is the solid wanted (evaporation/crystallisation) or is the liquid wanted (simple distillation)? For two miscible liquids use fractional distillation; for coloured dissolved substances use chromatography. Work through salt water, sand and water, ink, and ethanol–water as four contrasting examples.
The candidate balances a chemical equation by changing the subscripts inside a formula (writing H2O2 as H2O to make the count work) rather than placing coefficients in front of the formulae.
The candidate is focused on making the atom counts equal and treats the formula as adjustable arithmetic. The distinction between a subscript (part of the substance's identity) and a coefficient (a number of particles) is not firmly held.
What to do instead
Adopt a fixed procedure: list each element's atoms on both sides, then adjust only the large numbers in front of formulae, and never alter a subscript. After balancing, re-check that every formula still matches the correct substance name. Practise with a reaction where a common diatomic gas appears, such as hydrogen burning in oxygen, so the temptation to 'fix' H2 arises and is resisted.
The candidate describes an ionic bond as electrons being shared equally between a metal and a non-metal, and describes covalent bonding as one atom giving electrons away, so the resulting formulae and charges are wrong.
The words 'bond' and 'sharing' are generalised from covalent bonding, and the octet idea is applied without tracking which atom gains or loses electrons. The link between group number and ion charge is not automatic.
What to do instead
Fix the rule by element type: metal plus non-metal gives electron transfer and ions (ionic), non-metal plus non-metal gives sharing (covalent). Derive ion charges from group number (Group 1 → +1, Group 2 → +2, Group 17 → −1) and build the formula so total positive charge equals total negative charge. Check with sodium chloride and with water or carbon dioxide as contrasting examples.
The candidate confuses respiration with breathing and states that respiration happens only in the lungs, or claims that plants photosynthesise but do not respire.
Everyday language uses 'respiration' for breathing, and textbook diagrams place gas exchange in the lungs and photosynthesis in leaves, so the cellular process is mentally located in those organs only.
What to do instead
Define respiration as the cellular release of energy from glucose, occurring in all living cells all the time, and breathing as ventilation that supplies oxygen and removes carbon dioxide. Write the word equation for aerobic respiration and place it beside photosynthesis, noting that plants carry out both, with respiration continuing in darkness. Use a sprouting-seed or cut-flower experiment as evidence that non-lung tissue respires.
When reading a geological cross-section, the candidate orders rock layers by their vertical position on the page rather than applying superposition and cross-cutting relationships, so a folded or faulted sequence is dated incorrectly.
The rule 'lower is older' is learned on flat-lying strata and applied to diagrams where folding has turned layers over, or where an intrusion cuts across them. The candidate does not check whether the sequence has been disturbed.
What to do instead
Read the section in a fixed order: first identify any fold, fault, or intrusion, then apply superposition only to undisturbed sedimentary layers, then apply cross-cutting (a feature that cuts another is younger). State the reasoning in one sentence for each boundary. Practise on a diagram with a folded sequence plus a later intrusion so the two rules must be combined.