Québec Sec 4 Applied Science and Technology (057-410) common mistakes
Québec Sec 4 Applied Science and Technology (057-410) · Understand the traps and how to avoid them.
When asked to explain why a salt dissolves in water, the candidate describes only the stirring or the temperature and never mentions the attraction between water molecules and the ions, so the explanation stays at the level of 'it mixes' rather than describing particle-level dissociation.
In Sec 4 the particle model is taught mostly through diagrams and vocabulary, and candidates memorize 'dissolving is not a chemical change' without connecting it to the electrostatic attraction between the polar water molecules and the ionic crystal. Because stirring and heating do speed dissolution, the observable factors crowd out the explanatory one.
What to do instead
Before writing, force the answer into a two-step template: (1) name the particles (ions in the crystal, polar water molecules) and (2) name the interaction (attraction pulls ions off the surface and surrounds them). Practise by writing the same explanation for three different salts and check that the word 'attraction' or 'interaction' appears each time.
On a stoichiometry or concentration item the candidate sets up the ratio with quantities in mismatched units, for example putting a mass in grams directly against a molar mass in g/mol without converting, or using millilitres where litres are required in C = n/V.
Québec materials often present data in grams and millilitres because that is what a balance and graduated cylinder read, and candidates copy the numbers into the formula in the order they appear rather than first converting to the base units the formula assumes. Under time pressure the conversion step feels optional.
What to do instead
Adopt a mandatory pre-calculation line: rewrite every given quantity with its unit on its own line, circle any value not in g, mol, L, or J, and convert it before touching a formula. For concentration, always write V in litres explicitly. Do three drill problems where the trap is a millilitre value and confirm the answer changes by a factor of 1000 if you forget.
When distinguishing a chemical change from a physical change, the candidate uses a single observable cue such as bubbles or a colour change as proof, and misclassifies boiling, dissolving, or a phase change as chemical because 'something visible happened'.
The Sec 4 curriculum lists observable indicators of chemical change (gas, precipitate, colour change, heat) and candidates treat them as sufficient conditions rather than as hints that must be confirmed by a new substance forming. Boiling produces bubbles and a colour change can come from dilution, so the cue alone is unreliable.
What to do instead
Apply a two-question test every time: can the original substance be recovered by a physical means, and is a new substance with new properties present? Write the answer as 'bubbles alone is not enough because...' and give one counterexample (boiling water, diluting juice). Keep a personal list of ambiguous cases with the correct classification.
The candidate reads a technical drawing or exploded diagram and reports a dimension or part without checking the scale, the projection (first-angle versus third-angle), or which view the measurement belongs to, so a length taken from the front view is applied to the side view.
School drawings are often reproduced without a visible scale bar, and candidates assume any number on the sheet applies globally. First-angle and third-angle projection place the same view in different positions, and many students have only practised one convention, so they default to the layout they have seen most.
What to do instead
Before extracting any number, state aloud which view you are reading, whether a scale is given, and what the projection symbol shows. If no scale exists, say the dimension is not measurable and explain what additional information is needed. Practise by taking one drawing and listing the front, top, and side dimensions separately.
When analysing a mechanism, the candidate counts the driver and the driven component as the same thing or ignores the direction of force transmission, so a gear train or pulley system is described as 'the big gear turns the small one faster' without specifying which is the input and without computing the ratio.
Diagrams show arrows that students read as decoration, and the vocabulary of driver/driven is often learned as labels rather than as a causal chain. Candidates also confuse rotational speed with torque, assuming the faster output always means more force.
What to do instead
For every mechanism, write three lines before answering: input component, output component, and the ratio (teeth or radii) with its direction (speed up or force up). Then state the trade-off explicitly: a speed increase comes with a torque decrease. Redo one gear and one pulley problem using this template until it is automatic.
On an electricity item the candidate treats current as something that is 'used up' by each component in a series circuit, so they predict that the current after a resistor is smaller than before it, or they add voltages across parallel branches as if they were in series.
Everyday language ('the battery is used up', 'the bulb consumes current') reinforces a wrong mental model, and the Sec 4 treatment of Ohm's law is often formula-driven without a circuit-model check. Series and parallel rules look similar on paper, so candidates apply whichever they memorized last.
What to do instead
Draw the circuit and annotate it before calculating: mark series nodes where current is identical and parallel nodes where voltage is identical. Write the conservation statement in words ('charge entering a junction equals charge leaving'). Then check any numerical answer against that statement; if the current changed across a series resistor, the setup is wrong.
When explaining an adaptation, the candidate writes a teleological statement such as 'the giraffe grew a long neck because it needed to reach the leaves', presenting need as the cause of the trait.
Adaptation is taught through examples that emphasize function, and function language slips easily into purpose language. The distinction between individual acclimatization and population-level selection across generations is abstract and is rarely tested with a counterexample in class.
What to do instead
Use a fixed sentence frame: 'Individuals with [variation] survived and reproduced more often in [environment], so [trait] became more frequent in the population over generations.' Ban the words 'needed' and 'in order to' from adaptation answers and rewrite any answer that contains them. Practise with one plant and one animal example.
When asked to explain how a body system maintains homeostasis, the candidate names the organ and the hormone but omits the feedback loop, so the answer reads 'the pancreas controls blood sugar' with no sensor, no response, and no return to the set point.
Textbook diagrams show the loop, but exam answers are written in prose where the arrows disappear. Candidates also conflate the sensor and the effector, and negative feedback is often memorized as a phrase without being applied to a specific variable.
What to do instead
Write homeostasis answers as a numbered loop: variable deviates, sensor detects, control centre compares to set point, effector responds, variable returns toward set point. Include one sentence on what would happen if the loop failed. Do this for blood glucose and body temperature and compare the two structures.
On a geology or astronomy item the candidate confuses the time scale, treating the formation of the Solar System, the age of the Earth, and the timing of a rock layer as comparable, or reading a stratigraphic column as if the top layer were oldest.
Deep time is not intuitive, and superposition is stated once and then assumed. Diagrams of rock layers are read like graphs, where the top is the latest data point, which happens to be correct for superposition but for the wrong reason, so the rule collapses when a fold or intrusion appears.
What to do instead
Before interpreting any column, write 'oldest at the bottom unless disturbed' and then check for cross-cutting intrusions or folds that break the rule. Keep a single ordered timeline card with the Earth's age, the Solar System's age, and the major eras, and refer to it rather than guessing magnitudes.
When reporting an experiment, the candidate states a conclusion that goes beyond the data, for example claiming a general law from three trials, or omits the controlled variables and the uncertainty, presenting a single measurement as exact.
Lab reports are often graded on getting the 'right' answer, so candidates write the expected conclusion instead of the supported one. Significant figures and uncertainty are taught as rules to apply at the end rather than as part of the measurement, so they are dropped when the candidate is focused on the result.
What to do instead
Use a conclusion frame with three slots: what the data show (with the range and number of trials), what they do not show, and one source of error with its direction of effect. State the controlled variables in the method before writing the conclusion. For any number, report it to the precision the instrument allows and say so explicitly.