Science

Chemistry and materials includes Atoms and system boundaries.

This unit includes the lesson on atom counts and the boundary of the weighed system.

Chemistry and materials includes Evaluate the evidence.

This unit includes a lesson on repeated measurements and evaluating an investigation.

Atoms and system boundaries helps explain Evaluate the evidence.

Atom conservation and system boundaries help explain the measurement patterns. Measurements also need checks for losses and uncertainty.

Atoms and system boundaries checked by Why does sealed mass stay the same?.

The sealed-apparatus question checks whether gas and its atoms are still included in the weighed system.

Atoms and system boundaries applied in Draw and explain a particle model.

The drawing task applies conservation by regrouping six H atoms and three O atoms and explaining the model's limits.

Evaluate the evidence checked by What is wrong with adding the lid?.

The lid question checks whether the same apparatus is included before and after the reaction.

Evaluate the evidence applied in Compare open and closed measurements.

The data task applies signed changes, means and controls to the supplied open- and closed-system measurements.

Chemistry and materials includes Acids and alkalis.

The chemistry unit includes this introductory acids lesson and a separate soluble-salts lesson. Quantitative salt preparation and further acid reactions remain wider unit gaps.

Acids and alkalis explains Read the pH scale.

The lesson introduces how the pH scale classifies the aqueous solutions near room temperature used in its examples.

Acids and alkalis explains Partial neutralisation.

The lesson explains why some acid can react while the mixture remains acidic because acid is still in excess.

Read the pH scale helps interpret Partial neutralisation.

A changed pH must still be classified: becoming less acidic is not enough to establish a neutral mixture.

Read the pH scale applied in Interpret the pH table.

Use the scale to classify the supplied readings at 9, 10 and 11 mL; these illustrative data belong to the stated acid–alkali model.

Partial neutralisation checked by Does pH 5 mean neutral?.

The existing question asks whether changing from pH 2 to pH 5 establishes neutrality. It checks the distinction between partial reaction and a neutral reading.

Interpret the pH table extended by Challenge the midpoint claim.

The independent task challenges an exact midpoint claim using different readings. A measurement between them tests the claim; it does not prove the result in advance.

Partial neutralisation applied in Challenge the midpoint claim.

The transfer task requires evidence for the neutral point rather than assuming pH varies linearly with the volume added.

Chemistry and materials includes Form and separate salts.

This chemistry unit includes the soluble-salts lesson as an introductory extension towards GCSE. Grade 8 is a suggested placement, not an official requirement.

Form and separate salts develops Name the products.

The lesson develops this skill through its linked explanation or worked activity: name the products. Open the node to revisit that exact section.

Name the products tested by Question 1: Predict products.

Match the acid to the salt name and distinguish a metal oxide base from a metal. Apply that reasoning to the independent zinc oxide and nitric acid question.

Form and separate salts develops Follow the two filters.

The lesson develops this skill through its linked explanation or worked activity: follow the two filters. Open the node to revisit that exact section.

Follow the two filters tested by Question 2: Track the collected substance.

The process diagram distinguishes excess oxide removed first from salt crystals collected later. The question checks which solid each filter retains.

Form and separate salts develops Account for mass.

The lesson develops this skill through its linked explanation or worked activity: account for mass. Open the node to revisit that exact section.

Account for mass tested by Question 3: Account for water leaving.

Use the lesson’s system-boundary reasoning with the question’s fresh mass data. Remove unused oxide before inferring water loss; remaining solution mass is not pure-salt yield.

Form and separate salts develops Compare recoveries.

The lesson develops this skill through its linked explanation or worked activity: compare recoveries. Open the node to revisit that exact section.

Compare recoveries tested by Question 4: Evaluate a recovery claim.

The transfer task distinguishes wet mass from recovered pure salt. The question applies this distinction to two groups with different surface-drying conditions and no purity results.

Form and separate salts develops Salt left in solution.

The lesson develops this skill through its linked explanation or worked activity: salt left in solution. Open the node to revisit that exact section.

Salt left in solution tested by Question 5: Interpret remaining solution.

The lesson explains that crystallisation need not recover all dissolved salt. Additional crystals in the question are evidence of salt left in solution, not proof that earlier crystals were impure.

Form and separate salts develops Limits of filtration.

The lesson develops this skill through its linked explanation or worked activity: limits of filtration. Open the node to revisit that exact section.

Limits of filtration tested by Question 6: Challenge a separation claim.

The method section explains why dissolved excess reactant passes through ordinary filter paper. Apply that limitation to the question’s excess acid; a clear filtrate does not establish purity.

Physics and technology includes Current in a series circuit.

This physics unit includes introductory series-current, potential-difference and resistance lessons. Grade 8 is a suggested placement; combined resistances and parallel networks remain further study.

Current in a series circuit develops Trace a complete loop.

The lesson develops this skill through the linked diagram, explanation or activity: trace a complete loop. Open the node to revisit that section before trying the question.

Trace a complete loop tested by Question 1: Complete the conducting path.

The lesson diagram shows one conducting route through both cell terminals and the lamp. Use that route to choose a connection without leaving a terminal disconnected or bypassing the lamp.

Current in a series circuit develops Place the ammeter.

The lesson develops this skill through the linked diagram, explanation or activity: place the ammeter. Open the node to revisit that section before trying the question.

Place the ammeter tested by Question 2: Choose an ammeter connection.

The supervised measurement plan inserts the ammeter into the single path. The question distinguishes that arrangement from adding a low-resistance branch across the cell or resistor.

Current in a series circuit develops Separate current from energy.

The lesson develops this skill through the linked diagram, explanation or activity: separate current from energy. Open the node to revisit that section before trying the question.

Separate current from energy tested by Question 3: Separate current from energy.

The two-lamp transfer task keeps one steady current throughout the unbranched circuit. Apply that idea to different lamps: equal current alone does not mean equal brightness or equal energy transferred per second.

Current in a series circuit develops Compare means and ranges.

The lesson develops this skill through the linked diagram, explanation or activity: compare means and ranges. Open the node to revisit that section before trying the question.

Compare means and ranges tested by Question 4: Compare means and ranges.

The lesson separates a mean, observed spread and accuracy evidence. Calculate the new samples in the question; a smaller range alone cannot establish that a meter is closer to the true current.

Current in a series circuit develops Separate time and position.

The lesson develops this skill through the linked diagram, explanation or activity: separate time and position. Open the node to revisit that section before trying the question.

Separate time and position tested by Question 5: Distinguish position from time.

The controlled plan checks changing conditions when moving a meter. Use the question’s time order and repeated positions to challenge a claim that lower later readings prove current is used up.

Current in a series circuit develops Question meter accuracy.

The lesson develops this skill through the linked diagram, explanation or activity: question meter accuracy. Open the node to revisit that section before trying the question.

Question meter accuracy tested by Question 6: Evaluate a consistent meter offset.

The lesson warns that repeated readings or display resolution do not establish accuracy. The question adds explicit reference evidence for an idealised offset correction; repeats alone do not remove that offset.

Physics and technology includes Potential difference and energy transfer.

Physics and technology includes this introductory potential-difference lesson. Grade 8 is a suggested placement, not an official grade requirement.

Current in a series circuit supports Potential difference and energy transfer.

The series-current transfer task separates charge flow from energy transfer. This supports the voltage lesson: components in one steady series path carry the same current, but can transfer different amounts of energy per coulomb.

Potential difference and energy transfer develops Choose the meter endpoints.

The lesson develops this skill through the linked explanation or activity: choose the meter endpoints. Revisit that section before trying the question.

Choose the meter endpoints tested by Question 1: Choose the measured component.

The lesson plan identifies the two ends of the component before adding a voltmeter in parallel. Apply that method to B and C in the new circuit: spanning both resistors or inserting the meter into the main path measures a different arrangement.

Potential difference and energy transfer develops Use energy per charge.

The lesson develops this skill through the linked explanation or activity: use energy per charge. Revisit that section before trying the question.

Use energy per charge tested by Question 2: Use energy per charge.

The lesson defines volts as joules per coulomb. Use matching energy and charge values to find voltage, then apply that voltage to the additional charge in the question; charge is not consumed.

Potential difference and energy transfer develops Balance voltage, keep current.

The lesson develops this skill through the linked explanation or activity: balance voltage, keep current. Revisit that section before trying the question.

Balance voltage, keep current tested by Question 3: Use terminal voltage and series current.

The lesson balances component energy transfers per charge against the operating supply terminal voltage. Use the measured voltage rather than its printed rating, while retaining the same steady current throughout the unbranched series path.

Potential difference and energy transfer develops Interpret a signed mismatch.

The lesson develops this skill through the linked explanation or activity: interpret a signed mismatch. Revisit that section before trying the question.

Interpret a signed mismatch tested by Question 4: Evaluate a small mismatch.

The data discussion defines supply minus the component sum and distinguishes display resolution from accuracy. Apply both ideas to the fresh readings; a small residual alone does not establish its cause or agreement within an unknown uncertainty.

Potential difference and energy transfer develops Compare the same steady state.

The lesson develops this skill through the linked explanation or activity: compare the same steady state. Revisit that section before trying the question.

Compare the same steady state tested by Question 5: Separate changes over time from a voltage balance.

The plan monitors supply stability when moving a meter. Use the time order in the question: a component sum matching the average supply is an arithmetic coincidence, not evidence that the sequential readings describe one simultaneous state.

Potential difference and energy transfer develops Test an offset model.

The lesson develops this skill through the linked explanation or activity: test an offset model. Revisit that section before trying the question.

Test an offset model tested by Question 6: Apply a stated systematic-error model.

The data discussion warns that repeats alone do not remove systematic error. The question supplies an explicit additive-offset model: correct every reading, because one supply offset minus two component offsets does not cancel completely.

Physics and technology includes Resistance, current and potential difference.

Physics and technology includes this introductory resistance lesson. Grade 8 is a suggested placement, not an official grade requirement.

Potential difference and energy transfer supports Resistance, current and potential difference.

The potential-difference plan identifies the two ends of a component before placing a voltmeter across it. Resistance builds on this: match that voltage with current through the same component before calculating V/I.

Resistance, current and potential difference develops Convert current to amperes.

The lesson develops this skill through the linked explanation or activity: convert current to amperes. Revisit that section before trying the question.

Convert current to amperes tested by Question 1: Convert milliamperes before dividing.

The lesson converts milliamperes to amperes before dividing voltage by current. Apply that unit conversion to the new operating point; using the milliampere number directly gives a resistance a thousand times too small.

Resistance, current and potential difference develops Match across and through.

The lesson develops this skill through the linked explanation or activity: match across and through. Revisit that section before trying the question.

Match across and through tested by Question 2: Use readings for the intended resistor.

Use the potential difference across the intended resistor and the current through that same resistor. The supply spans both resistors, while the single steady series path carries the same current through each; neither the supply voltage nor half the current describes R2 alone.

Resistance, current and potential difference develops Compare voltage/current ratios.

The lesson develops this skill through the linked explanation or activity: compare voltage/current ratios. Revisit that section before trying the question.

Compare voltage/current ratios tested by Question 3: Compare unequal-voltage cases.

A smaller current indicates greater resistance only when potential difference is held fixed. In the question the voltages differ, so convert both currents and compare each component’s own V/I ratio rather than ranking currents alone.

Resistance, current and potential difference develops State the model condition.

The lesson develops this skill through the linked explanation or activity: state the model condition. Revisit that section before trying the question.

State the model condition tested by Question 4: State the condition behind a prediction.

The lesson distinguishes a resistance calculated at one operating point from a constant-resistance model. Apply I = V/R at the new voltage only under the question’s stated unchanged-resistance condition; an initial reading alone cannot establish that condition.

Resistance, current and potential difference develops Test whether the ratio changes.

The lesson develops this skill through the linked explanation or activity: test whether the ratio changes. Revisit that section before trying the question.

Test whether the ratio changes tested by Question 5: Test a model against a data pattern.

Calculate V/I for each matching pair in the constructed table. Differing ratios reject one constant-resistance value for these exact data, but do not prove that heating is the unique cause; real investigations also require checking conditions and instruments.

Resistance, current and potential difference develops Plan valid meter connections.

The lesson develops this skill through the linked explanation or activity: plan valid meter connections. Revisit that section before trying the question.

Plan valid meter connections tested by Question 6: Choose a valid measurement plan.

The measurement plan places an ammeter in series and a voltmeter across the resistor. Apply the same arrangement to P and Q, with suitable low-voltage equipment, brief low-current readings and checks for temperature drift. Written planning is not practical certification.