Kagoshima Entrance Science common mistakes
Kagoshima Entrance Science · Understand the traps and how to avoid them.
When asked to find the resultant force on an object, the candidate adds the magnitudes of two forces acting in opposite directions instead of subtracting the smaller from the larger, then reports the sum as the net force.
The candidate has memorised 'net force = add the forces' from problems where all forces point the same way, and does not draw a free-body diagram or assign a positive direction before calculating.
What to do instead
Before any calculation, draw the object as a dot and draw each force as an arrow from it with its true direction. Choose one direction as positive, write each force with a + or − sign, then sum algebraically. State the direction of the resultant explicitly, not just its size.
The candidate writes the mirror or lens equation and substitutes the object distance and focal length without converting centimetres to metres, or mixes the two units within one calculation, producing an answer off by a factor of 100.
Textbook diagrams are drawn in centimetres while formulas in the candidate's notes use metres, and the candidate copies numbers straight from the question stem without checking units.
What to do instead
Write the given values in a column with their units, convert everything to one unit (usually metres) before substituting, and carry the unit through the working. Check that the final answer's magnitude is physically sensible for the setup described.
The candidate balances a chemical equation by changing the subscripts inside a formula (for example turning H2O into H2O2 or Fe2O3 into FeO) so that the atom counts match, rather than placing coefficients in front of the formulas.
The candidate treats the equation as an arithmetic puzzle to be solved rather than a statement of which substances are present, and has not internalised that a subscript is part of the substance's identity.
What to do instead
Write every formula first and lock it: draw a box around each formula and allow yourself to write numbers only in front of the boxes. Balance one element at a time, starting with elements that appear in only one reactant and one product, and leave hydrogen and oxygen until last.
On an ionic equation or neutralisation question, the candidate writes the full molecular equation when asked for the ionic equation, or leaves spectator ions such as Na+ and Cl− in the final equation.
The candidate does not distinguish between 'all the ions present in the beaker' and 'the ions that actually react', and has not practised identifying which ions are unchanged on both sides.
What to do instead
Write the full equation, then split every soluble ionic compound into its ions. Cross out any ion that appears identically on both sides, and copy only what remains. Finish by checking that both charge and atom count balance in the shortened equation.
When describing a cell, the candidate lists the nucleus, cytoplasm and cell membrane but omits structures that distinguish plant from animal cells, or claims that animal cells have a cell wall or chloroplasts.
The candidate learns a single generic 'cell diagram' and does not build a comparison table, so the distinguishing features (cell wall, chloroplasts, large permanent vacuole) are not anchored to the correct cell type.
What to do instead
Make a two-column table of plant versus animal cell structures and learn it as a contrast, not a list. For every structure you name, be able to say what it does and which cell types have it. Practise by labelling blank diagrams of both cell types from memory.
In a genetics cross, the candidate writes the parental genotypes but then fills the Punnett square with the gametes' genotypes rather than with one allele from each parent per box, so the offspring genotypes are wrong even though the parental genotypes were correct.
The candidate does not separate the two stages of meiosis (forming gametes, each carrying one allele) from fertilisation (combining one allele from each gamete), and rushes to fill the grid.
What to do instead
Always write the gametes along the top and side first, each containing exactly one allele per gene, and check that step before filling any box. Then combine one column letter with one row letter per square. Finish by stating the phenotype ratio and checking it sums correctly.
When asked to predict the effect of removing a predator or a producer from a food web, the candidate says only that the prey 'will increase' and stops, without tracing the knock-on effect through the rest of the web or considering that the increase will later be limited.
The candidate reasons about a single link rather than the whole network, and does not consider competition, food supply or carrying capacity.
What to do instead
Answer in a chain: state the direct effect on the organism next to the removed one, then the effect on what that organism eats, then on what eats it, naming each organism. Add one sentence on a limiting factor, such as food shortage or competition, that would eventually reverse or cap the change.
Given a geological cross-section described in words, the candidate identifies the folded or faulted layer as the oldest simply because it lies lowest on the page, ignoring that folding or faulting has overturned the original order.
The candidate applies the principle of superposition mechanically without checking whether the sequence has been disturbed, and does not consider cross-cutting relationships.
What to do instead
Before assigning any age, ask three questions in order: has anything cut across the layers (a fault or intrusion is younger than what it cuts)? have the layers been folded or tilted (restore them to horizontal first)? only then apply superposition. Write the reasoning steps as numbered sentences in the answer.
When explaining why a warm air mass rising over a cold air mass produces rain, the candidate says 'warm air rises and becomes rain' without mentioning cooling by expansion, condensation onto condensation nuclei, or cloud droplet growth.
The candidate compresses a multi-step mechanism into a slogan and has not practised sequencing the physical steps in order.
What to do instead
Learn the chain as four labelled steps: air is forced upward, it expands and cools adiabatically, water vapour condenses on nuclei to form cloud droplets, droplets coalesce and grow heavy enough to fall. Write the chain out for both frontal and convectional rainfall and compare where they differ.
On a question about the apparent motion of the Sun or stars, the candidate explains the daily east-to-west movement using Earth's orbit around the Sun rather than Earth's rotation on its axis, conflating daily and annual motion.
Both motions involve the Earth moving, and the candidate has not separated the time scales or the axis involved, so the two explanations blur together.
What to do instead
Make a table with two rows, 'rotation' and 'revolution', and for each record the period, the axis or path, and the observable effect (daily rising and setting versus seasonal change in the Sun's altitude and constellation visibility). Before answering, decide which time scale the question describes, then choose the matching row.
When asked to evaluate an experiment, the candidate states that a variable was not controlled but cannot name which variable, or describes the conclusion as 'proving' the hypothesis when the data only support it.
The candidate treats 'control the variables' and 'prove' as phrases to insert rather than claims that must be tied to the specific setup described in the question.
What to do instead
Name the variable explicitly and say what it should have been held at, for example 'the temperature of the water was not kept the same in both trials'. Replace 'proves' with 'supports' or 'is consistent with', and add what further data would be needed to strengthen the conclusion.
When reading a table or graph, the candidate reports a value read from the axis without its unit, or quotes the reading at a precision the scale does not allow, such as giving a temperature to two decimal places from a graph marked in whole degrees.
The candidate focuses on getting a number and treats units and precision as decoration, and does not check the smallest division of the scale before reading.
What to do instead
Before reading any value, note the unit on each axis and the size of the smallest marked division, and quote readings to that precision with the unit attached. If interpolating between marks, say so, for example 'approximately 23 degrees Celsius, read between the 20 and 30 marks'.