Toyama Prefectural Public High School Entrance Examination - Science common mistakes
Toyama Prefectural Public High School Entrance Examination - Science · Understand the traps and how to avoid them.
When asked about the forces on a book resting on a desk, the student writes that 'the gravitational force from the Earth on the book and the upward normal force from the desk are an action–reaction pair, so they cancel.'
Japanese textbooks teach 力のつり合い (two forces on ONE object) and 作用・反作用 (forces on TWO different objects) using the same visual cue - two equal, opposite arrows - and the student pattern-matches on 'equal and opposite' without checking which object each force acts on.
What to do instead
Require a two-object check on every force diagram: label each arrow as '[from X on Y]'. Balanced forces share the same Y; an action–reaction pair always has Y1 ≠ Y2. Drill the three standard cases (book on desk, swimmer pushing a wall, two magnets repelling) until the label is automatic.
In a series circuit with two different resistors, the student claims the current decreases as it passes through each resistor - e.g., '1 A leaves the battery, 0.6 A leaves the first resistor' - and writes different current values for each series element.
Everyday intuition treats a battery as something being 'used up', and the student unconsciously blends the series rule (current constant) with the parallel rule (current splits), because both appear in the same unit and are diagrammed similarly.
What to do instead
Enforce a two-line labelling convention on every circuit diagram: (1) write the current on every branch and add the explicit equation 'series ⇒ same current everywhere'; (2) write the voltages and use V_total = V1 + V2 for series. Follow with predict-and-check exercises on three circuits where one element is changed.
The student measures the angle of incidence or reflection from the mirror surface instead of from the normal, and in refraction questions draws the ray bending away from the normal when light passes from air into glass.
The mirror or boundary is the visually dominant line in the exam figure, so the student anchors on it. Also 'angle of incidence = angle of reflection' is memorised as a number equality without the reference line being fixed in the mental model.
What to do instead
Make drawing the dotted normal the mandatory first step, then mark the angle with an arc between the ray and the normal (never the surface). For refraction, memorise 'entering a denser medium ⇒ bend toward the normal; leaving it ⇒ bend away'. Apply to air→glass, glass→air, and water→air in the same session so the rule is seen as directional.
The student writes 'the ball's energy disappears once it stops bouncing' or 'friction used up the energy', rather than accounting for it as sound and thermal energy.
Students treat energy as a substance that is consumed rather than as a conserved quantity that changes form, and exam questions that ask 'where did the energy go?' are not the format they practised when first learning the term エネルギー.
What to do instead
Use a fixed transfer sentence frame: '[form] of [object] → [form] of [object/ surroundings], plus [loss form]'. Work the bouncing-ball case fully (位置 → 運動 → 音・熱) and require the written answer to state that the total is unchanged.
The student writes ionic-compound formulas by 'reading the name' - MgCl, CaOH, NaSO4 - and writes skeleton equations that are not balanced, such as H2 + O2 → H2O.
Charge balancing was learned as a rule for a few simple cases and the student reverts to name-to-symbol transcription under time pressure, without checking that total positive and negative charge are equal.
What to do instead
Use the cross-charge method explicitly: write each ion with its charge above the symbol, cross the numbers down as subscripts, then reduce. For every equation, finish with an atom count on both sides and adjust coefficients. Set of ten formulas and five equations per practice round, with the counting step mandatory.
The student mixes up 陽極 and 陰極 in electrolysis questions, and predicts a precipitate whenever two solutions are mixed - for example expecting a solid from sodium chloride solution plus potassium nitrate solution.
The kanji 陽/陰 is read as 'positive/negative terminal' from everyday electronics rather than as the electrode where oxidation/reduction occurs, and precipitation is memorised as 'ions react' without a solubility check.
What to do instead
Build a small 'insoluble pairs' card (Ag+ with Cl−, Ba2+ and Ca2+ with SO4^2−, Pb2+ with Cl−/SO4^2−) and a matching 'no reaction' card. For electrolysis, attach the hook 陽極＝酸化, 陰極＝還元 and always write which ion moves to which electrode before naming the product.
The student states that respiration is simply the reverse of photosynthesis and therefore absorbs energy, and that all chemical reactions release heat.
Endothermic reactions are introduced through a single demonstration, so the student generalises from the more memorable combustion and neutralisation examples and treats 'reaction' as synonymous with 'heat released'.
What to do instead
Have the student sort ten reactions into 発熱 and 吸熱 with a one-line justification each: combustion, neutralisation, calcium oxide plus water (発熱); photosynthesis, ammonium chloride plus barium hydroxide, thermal decomposition of sodium hydrogen carbonate (吸熱). Insist on the exact wording '熱を放出する／吸収する' in every answer.
The student writes that plants photosynthesise in the daytime and respire at night, and confuses xylem (water and inorganic salts, upward) with phloem (organic matter, leaf to the rest of the plant).
Day-versus-night framing is intuitive and fits the visible light dependence of photosynthesis, and the two transport tissues are described with overlapping vocabulary in the same chapter.
What to do instead
Build a 24-hour table for a plant: photosynthesis daytime only; respiration day AND night; transpiration mostly daytime. For transport, memorise xylem as 'root → leaf, water and minerals' and phloem as 'leaf → whole plant, organic matter', and draw a stem cross-section labelling both.
In genetics questions the student writes the genotype ratio in the phenotype answer slot (or vice versa), and states that a 3:1 ratio is expected among the offspring of a single pair cross rather than of a heterozygote × heterozygote cross.
遺伝子型 and 表現型 are easily swapped, and the student compresses the two-step reasoning (square → genotype ratio → phenotype ratio) into one step, losing track of which generation (F1 or F2) the question is asking about.
What to do instead
Require every Punnett square answer to carry two output rows: 'genotype ratio = …' and 'phenotype ratio = …', with the generation stated in words. Practise Aa × Aa (1:2:1 / 3:1) and Aa × aa (1:1 / 1:1) side by side so the difference is visible.
The student uses 震源 when the question asks about distance from the point directly above it, labels the surface point as the focus, and writes that the first waves to arrive at a station are the large-amplitude S-waves.
震源 and 震央 differ by one character and sit close together in the standard cross-section diagram, while P-wave and S-wave properties are learned as a paired list that is easy to invert under time pressure.
What to do instead
Anchor on 'P = Primary = 初期微動 = faster, longitudinal' and 'S = Secondary = 主要動 = slower, transverse'. Redraw the layered cross-section with the focus marked ● and the epicenter ▲, labelled in kanji, and practise reading all distances from the epicenter unless the question explicitly says 震源.