Iwate Entrance Science common mistakes
Iwate Entrance Science · Understand the traps and how to avoid them.
When simplifying algebraic expressions or solving equations, the candidate cancels a term across a sum instead of a factor, e.g. rewriting (x+3)/x as 3 or cancelling x in (x²+1)/x to get x+1.
The candidate has over-generalised the cancellation rule from products to sums and is pattern-matching on the visual appearance of the symbol rather than checking that the operation is valid only when the same factor multiplies the whole numerator and denominator.
What to do instead
Before cancelling, force the candidate to factorise the numerator and denominator completely and write them as a product; if a term is joined by + or −, it cannot be cancelled. Practise ten mixed items where the candidate must state 'factor or term?' for each part before simplifying, and verify by substituting x = 2 into the original and simplified forms.
On a definite integral or area problem, the candidate computes the antiderivative but substitutes the limits in the wrong order or forgets to subtract, and on area between curves they integrate without splitting at the intersection points, giving a signed value instead of a total area.
The candidate treats integration as a symbol-manipulation exercise and has not internalised that the definite integral accumulates signed area; intersection points and limit order feel like optional bookkeeping rather than the definition of the quantity asked.
What to do instead
Require a sketch of the region and explicit marking of intersection points before any integration, then write F(b) − F(a) with the limits labelled. After computing, sanity-check the sign and magnitude against the sketch (area cannot be negative). Drill one problem per session where the curves cross inside the interval so splitting is unavoidable.
In mechanics, the candidate resolves forces or velocities into components but mixes sine and cosine, or omits a force (often the normal force or the component of gravity along an incline), then substitutes numbers into a formula chosen by memorised keyword rather than by analysing the free body.
The candidate is formula-driven: they search the question for a trigger word and recall an equation, skipping the free-body diagram. Without a diagram, the geometry of which component is adjacent to the angle is guesswork, and omitted forces go unnoticed.
What to do instead
Make a labelled free-body diagram mandatory for every mechanics item, with axes chosen and every force drawn before any equation is written. Have the candidate state which direction is positive and write ΣF = ma along each axis separately. Check sine/cosine by the limiting case: at 0° the along-slope component must vanish.
When predicting organic reaction products, the candidate ignores regioselectivity and stereochemistry, giving a single flat product for a reaction that should yield a major and minor product or a specific stereoisomer, and fails to identify the functional group that actually reacts.
The candidate has memorised reaction names as isolated facts without the underlying electron-flow logic (which atom is nucleophilic or electrophilic, where the intermediate is stabilised), so they apply a reaction to the wrong site or forget that three-dimensional arrangement is part of the answer.
What to do instead
For each reaction, require the candidate to draw curly arrows from the nucleophile to the electrophile and mark the reactive site before naming products. Then explicitly answer three prompts: which site reacts, what is the major product and why (stability, Markovnikov, steric), and what is the stereochemical outcome. Build a one-page map linking functional group to characteristic reactions.
The candidate confuses the levels of protein or nucleic-acid structure, or describes enzyme behaviour by saying the enzyme is 'used up' or that raising temperature always increases rate, rather than identifying the active site, specificity and the denaturation threshold.
Terminology is learned as a list of labels (primary, secondary, tertiary) with no structural picture attached, and the rate-versus-temperature curve is memorised as 'goes up' rather than as a competition between kinetic energy and loss of tertiary structure.
What to do instead
Have the candidate draw and annotate each structural level with the bonds involved (peptide, hydrogen, ionic, disulfide) and explain what denaturation breaks. For enzymes, sketch the rate–temperature and rate–pH curves and mark the optimum and the denaturation region, then explain the shape in terms of active-site shape.
On genetics problems, the candidate sets up a Punnett square or pedigree but ignores that the trait may be sex-linked or that a parent may be heterozygous, and reports a ratio without stating the genotype–phenotype link or the probability basis.
The candidate defaults to a simple monohybrid 3:1 pattern and does not first establish the mode of inheritance from the data; they also confuse 'ratio of offspring' with 'probability for one offspring' and skip assigning genotypes to individuals in a pedigree.
What to do instead
Impose a fixed first step: from the pedigree or cross, decide dominance and whether the gene is autosomal or sex-linked, and write the genotype of every individual before drawing any square. Then compute probabilities per offspring and state the assumption. Include at least one sex-linked and one test-cross item in each practice set.
In data-interpretation questions, the candidate reads a value off a graph or table without checking the axis scale or units, and reports a conclusion that the data do not support, such as claiming causation from a correlation or extrapolating beyond the measured range.
The candidate treats the graph as an illustration rather than as evidence with a scale, uncertainty and limited range; the desire to give a definite answer overrides the discipline of stating only what the plotted points show.
What to do instead
Train a reading routine: state the axes, units and scale, read the value with its uncertainty, then phrase the conclusion as 'within the measured range, X is associated with Y' and explicitly note what would be needed to claim causation. Practise items that include a distractor option extrapolating past the last data point.
When describing an experiment, the candidate identifies variables vaguely ('keep it the same') and omits the control, the number of repeats, or how the dependent variable is measured, so the design cannot actually test the stated hypothesis.
The candidate has learned the words 'independent' and 'dependent variable' but not the operational step of turning a hypothesis into a measurable procedure, and treats the control group as an optional formality rather than the comparison that makes the result interpretable.
What to do instead
Use a template the candidate fills in every time: hypothesis, independent variable with the exact values to be tested, dependent variable with the instrument and unit, at least three controlled variables with how each is held constant, a negative control, and the number of repeats with the reason (reducing random error). Have them critique a flawed design against the same checklist.
In electromagnetism, the candidate applies Ohm's law or the right-hand rule without tracking direction and sign, mixing up current direction and electron flow, or treating a series/parallel combination as a single resistor without computing the equivalent resistance correctly.
The candidate holds a formula but no mental model of the circuit or field geometry, so the direction conventions and the rules for combining resistors are applied from memory under time pressure and errors in one branch propagate silently.
What to do instead
Redraw every circuit with conventional current arrows and label each resistor before calculating; compute equivalent resistance step by step (series adds, parallel reciprocals add) and check that the equivalent lies between the smallest and largest branch values. For fields, draw the field lines and apply the right-hand rule with the hand physically oriented, then verify the force direction against the sketch.
In thermodynamics, the candidate confuses heat with temperature and applies Q = mcΔT or the first law without accounting for phase change or work done, so a problem involving melting ice or an insulated gas expansion is solved with a single specific-heat term.
Heat and temperature are used interchangeably in everyday language, and the candidate has not separated the distinct stages of a heating process (warming solid, melting at constant temperature, warming liquid), so the latent-heat term is simply forgotten.
What to do instead
For any thermal problem, require a temperature-versus-heat sketch with each stage labelled and the corresponding term (mcΔT for each phase, mL for each transition) written on the sketch before calculating. For the first law, state the sign convention and identify which of Q, W and ΔU are zero in the given conditions. Include at least one multi-stage and one insulated-expansion item per practice set.