Physical Sciences IEB Grade 12 Subject Assessment Guidelines

PHYSICAL SCIENCES MEANS OF ASSESSMENT

• Paper 1 (Physics):
  • Duration: 3 hours.
  • Total Marks: 200 marks (The raw total is scaled out of 150 marks).
• Paper 2 (Chemistry):
  • Duration: 3 hours.
  • Total Marks: 200 marks (The raw total is scaled out of 150 marks).
• School-Based Assessment (SBA):
  • Total Marks: 100 marks.
• Total Marks for the Subject: 400 marks.

EXAMINATION REQUIREMENTS AND WEIGHTINGS

• Assessment Foundations: Tasks and questions are based on the Subject Assessment Syllabus.
• Examination Scheduling: The two papers are written on separate days.
• Questioning Styles: A variety of styles are used. A maximum of $10\%$ of the final marks are allocated to multiple-choice format questions.

Table 1: Physical Sciences Paper I (Physics) Content Weighting

• Kinematics (Motion in 1D): Approximately $50$ marks ($\pm 10$ marks); $25\%$ weight ($\pm 5\%$).
• Newton's Laws and Applications: Approximately $30$ marks ($\pm 10$ marks); $15\%$ weight ($\pm 5\%$).
• Momentum, Impulse, Work, Energy, and Power: Approximately $30$ marks ($\pm 10$ marks); $15\%$ weight ($\pm 5\%$).
• Gravitational and Electric Fields: Approximately $20$ marks ($\pm 10$ marks); $10\%$ weight ($\pm 5\%$).
• Electric Circuits: Approximately $30$ marks ($\pm 10$ marks); $15\%$ weight ($\pm 5\%$).
• Electrodynamics: Approximately $24$ marks ($\pm 10$ marks); $12\%$ weight ($\pm 5\%$).
• Photons and Electrons: Approximately $16$ marks ($\pm 10$ marks); $8\%$ weight ($\pm 5\%$).

Table 2: Physical Sciences Paper II (Chemistry) Content Weighting

• Quantitative Chemistry: Approximately $30$ marks ($\pm 10$ marks); $15\%$ weight ($\pm 5\%$).
• Chemical Bonding: Approximately $20$ marks ($\pm 10$ marks); $10\%$ weight ($\pm 5\%$).
• Energy Change & Rates of Reactions: Approximately $20$ marks ($\pm 10$ marks); $10\%$ weight ($\pm 5\%$).
• Chemical Equilibrium: Approximately $25$ marks ($\pm 10$ marks); $12,5\%$ weight ($\pm 5\%$).
• Acids and Bases: Approximately $25$ marks ($\pm 10$ marks); $12,5\%$ weight ($\pm 5\%$).
• Electrochemistry: Approximately $40$ marks ($\pm 10$ marks); $20\%$ weight ($\pm 5\%$).
• Organic Chemistry: Approximately $40$ marks ($\pm 10$ marks); $20\%$ weight ($\pm 5\%$).

COGNITIVE LEVEL TAXONOMY

Table 3.1: Weighting According to Taxonomy

• Level 1 (Knowledge and Recall): Physics $15\%$, Chemistry $15\%$.
• Level 2 (Comprehensions and Routine Exercises): Physics $35\%$, Chemistry $40\%$.
• Level 3 (Application and Analysis): Physics $40\%$, Chemistry $35\%$.
• Level 4 (Synthesis and Evaluation): Physics $10\%$, Chemistry $10\%$.

Table 3.2: Cognitive Level Descriptions and Examples

• Level 4: Synthesis & Evaluation:

  • Description: Requires synthesising knowledge across concepts to evaluate scenarios.
  • Physics Example: Given a car and a truck travelling toward each other; the truck has twice the mass. On impact, the car exerts force $F$ on the truck and experiences acceleration $a$. Learners must determine which driver is likely more injured using principles of acceleration and velocity.
  • Chemistry Example (Graph): A rate vs. time graph for acid ionisation; learners must determine the effect of a change shown on the graph on the solution's $\text{pH}$. Requires synthesis of reaction rates, equilibrium, and the $\text{pH} = -\log[H_3O^+]$ relationship.
  • Calculations: Multi-step calculations without scaffolding (e.g., Physics simultaneous equations; Chemistry $K_c$ problems where initial moles must be found from provided $K_c$).
  • New Contexts: Explaining how a microphone works (Physics) or why Aluminium cannot be produced via aqueous electrolysis of $Al^{3+}$ (Chemistry).

• Level 3: Application & Analysis:

  • Description: Analysis and interpretation of given situations (diagrams/descriptions).
  • Physics Examples: Determining the effect on internal resistance/voltmeter readings when moving a component in a circuit; calculation of maximum height in a pendulum-collision scenario using conservation of momentum and mechanical energy.
  • Chemistry Examples: Determining the $\text{emf}$ of a galvanic cell from a labelled diagram (no polarity given); writing the IUPAC name for a given ester structure.
  • Physical Property Explanation: Explaining why butane has a higher boiling point than methylpropane based on intermolecular force strength factors.

• Level 2: Comprehension:

  • Description: Explaining the "why" behind phenomena or relationships between concepts.
  • Chemistry Example: Explaining why increasing acid concentration increases the reaction rate with Zinc (Collision Theory).
  • Physics Example: Stating how photoelectron speed changes when incident radiation frequency increases.
  • Scientific Method: Identifying independent/dependent variables, drawing conclusions, or reading values from a graph.
  • Calculations: One-step calculations (e.g., $I = \frac{V}{R}$).
  • Routine Equations: Writing half-equations from the Standard Electrode Potential (SEP) table or balanced equations for $HCl$ ionisation.

• Level 1: Recall:

  • Description: Providing definitions, words, phrases, or learned descriptions.
  • Examples: Defining acceleration; naming the split-ring commutator in a DC motor; giving the chemical symbol for the carbonate ion ($CO_3^{2-}$); naming homologous series (e.g., carboxylic acids).

SCHOOL-BASED ASSESSMENT (SBA)

• Weighting: SBA constitutes $25\%$ of the total National Senior Certificate assessment.
• Reporting: Reported using a Seven-Point Rating Scale (Code 1 to 7):
  • 7: Outstanding Achievement ($80\text{-}100\%$)
  • 6: Meritorious Achievement ($70\text{-}79\%$)
  • 5: Substantial Achievement ($60\text{-}69\%$)
  • 4: Adequate Achievement ($50\text{-}59\%$)
  • 3: Moderate Achievement ($40\text{-}49\%$)
  • 2: Elementary Achievement ($30\text{-}39\%$)
  • 1: Not Achieved ($0\text{-}29\%$)

Table 5: SBA Component Requirements (Grade 12)

• Practical Investigations: 2 tasks (1 Physics focus, 1 Chemistry focus). Minimum 2 hours each. Weighted at $15\%$ each (Total $30\%$ of SBA).
• Controlled Tests: 2 tasks (1 Physics focus, 1 Chemistry focus). Minimum 40 minutes each. Midyear examinations or Alternative Assessments may substitute for one test. Weighted at $15\%$ each (Total $30\%$ of SBA).
• Preliminary Examinations: 2 papers (3 hours each). Weighted at $20\%$ each (Total $40\%$ of SBA).
• Total SBA Marks: 100.

PRACTICAL INVESTIGATIONS AND ALTERNATIVE ASSESSMENT

Practical Investigation Flowchart

1. Observations & Facts: Giving rise to investigative questions.
2. Hypothesis Development: Formulating a testable prediction.
3. Experimental Design: Planning to test the hypothesis.
4. Handling of Data: Manipulating equipment, measurement, and observation.
5. Evaluating Results: Considering reliability and validity to draw conclusions.
6. Theory: Integration of findings into scientific theory.

Skills Assessed in Investigations

• Hypothesis: Formulating questions, combining ideas with facts, making predictions.
• Manipulation: Correct choice and safe use of equipment, reading scales accurately.
• Planning: Identifying independent, dependent, and fixed (controlled) variables; understanding experimental validity and reliability (sample size/readings).
• Presentation: Tabulating and graphing (using software or data loggers).
• Analysis: Weighing advantages/disadvantages, addressing the hypothesis, identifying relationships.
• Communication: Reports, models, posters, or presentations.

Alternative Assessment Options

• Minimum duration: 1 hour. Referenced sources are required.
• Tasks include:
  1. Debate/Essay: Ethical issues in science (e.g., using articles from www.peep.ac.uk).
  2. Translation Task: Analysing scientific articles, journals, or video clips.
  3. Standard Experiment: Simplified practical where the question/procedure is provided (1-2 hours).
  4. Simulations: Data reviews of online simulations or "physics-in-action" videos.
  5. Metacognitive Task: Setting a test, preparing mark schemes, or identifying misconceptions.

MODERATION AND ADMINISTRATIVE PROTOCOLS

Levels of Moderation

• School Level: Monitoring of Formal Programme of Assessment at the start of the year; pre-moderation of tasks; principal-signed letter of authenticity.
• Cluster Level: Two meetings annually (before March 15 and September 15) to discuss standards, share resources, and complete file moderation.
• IEB Level: Regional moderation by mid-October; national moderation in December. Moderators check compliance, task standards, and marking consistency. Changes to school marks may be recommended if standards are not met.

Documentation Requirements

• Learner's File: Contains all SBA work listed in Table 5; flat folder format; indexed with marks and declaration of authenticity.
• Teacher's File: Contains assessment task sheets, marking schemes, rubrics, Appendix A (Task Planning Sheet) for prelims, evidence of moderation, and references for all sources used in tasks.
• Absence: Learners must provide a doctor's letter and complete equivalent makeup tasks.

PHYSICS EXAMINATION DATA SHEET: CONSTANTS AND FORMULAE

Physical Constants

• Acceleration due to gravity: $g = 9,8\,m \cdot s^{-2}$
• Speed of light in vacuum: $c = 3,0 \times 10^8\,m \cdot s^{-1}$
• Gravitational constant: $G = 6,7 \times 10^{-11}\,N \cdot m^2 \cdot kg^{-2}$
• Coulomb constant: $k = 9,0 \times 10^9\,N \cdot m^2 \cdot C^{-2}$
• Charge on electron: $e = 1,6 \times 10^{-19}\,C$
• Electron mass: $m_e = 9,1 \times 10^{-31}\,kg$
• Planck's constant: $h = 6,6 \times 10^{-34}\,J \cdot s$
• One electron-volt: $1\,eV = 1,6 \times 10^{-19}\,J$

Motion Formulae

• $v = u + at$
• $s = \left(\frac{v + u}{2}\right)t$
• $v^2 = u^2 + 2as$
• $s = ut + \frac{1}{2}at^2$
• Alternative notation: $v_f = v_i + a\Delta t$; $\Delta x = \left(\frac{v_f + v_i}{2}\right)\Delta t$; $\Delta x = v_i\Delta t + \frac{1}{2}a(\Delta t)^2$

Force and Momentum

• $F_{net} = ma$
• $p = mv$
• $F_{net} = \frac{\Delta p}{\Delta t}$
• $J = \Delta p = F_{net}\Delta t = m(v - u)$
• $F_g = mg$
• $F_{fs(\max)} = \mu_s F_N$
• $F_{fk} = \mu_k F_N$

Work, Energy, and Power

• $W = Fs\cos(\theta)$
• $E_k = \frac{1}{2}mv^2$
• $E_p = mgh$
• $W_{net} = \Delta E_k$
• $P = \frac{W}{t} = Fv$
• $\%\,\text{Efficiency} = \frac{P_{out}}{P_{in}} \times 100$

Gravitation and Fields

• $F = G\frac{m_1 m_2}{r^2}$
• $g = \frac{F}{m} = G\frac{M}{r^2}$
• $F = k\frac{q_1 q_2}{r^2}$
• $E = \frac{F}{q} = k\frac{Q}{r^2}$

Electric Circuits

• $V = \frac{W}{q}$
• $I = \frac{q}{t}$
• $R = \frac{V}{I}$
• $R_s = R_1 + R_2 + \dots$
• $\frac{1}{R_p} = \frac{1}{R_1} + \frac{1}{R_2} + \dots$
• $\text{emf} = I(R_{ext} + r) = V_{load} + V_{internal}$
• $W = VIt = I^2 Rt = \frac{V^2}{R}t$
• $P = VI = I^2 R = \frac{V^2}{R}$

Electrodynamics

• $\Phi = BA\cos(\theta)$
• $\text{emf} = -N\frac{\Delta \Phi}{\Delta t}$
• $F = IB\ell\sin(\theta)$
• $\frac{N_s}{N_p} = \frac{V_s}{V_p}$
• $V_p I_p = V_s I_s \text{ (ideal transformer)}$

Photons and Electrons

• $c = f\lambda$
• $E = hf = \frac{hc}{\lambda}$
• $E = W_0 + E_{k(\max)}$
• $W_0 = hf_0$
• $E_{k(\max)} = \frac{1}{2}mv_{\max}^2$

CHEMISTRY EXAMINATION DATA SHEET: CONSTANTS AND FORMULAE

Physical Constants (Chemistry)

• Standard Pressure: $p^\theta = 1,01 \times 10^5\,Pa$
• Molar gas volume at STP: $V_m = 22,4\,dm^3 \cdot mol^{-1}$
• Standard Temperature: $T^\theta = 273\,K\, (0\,^{\circ}C)$
• Avogadro's constant: $N_A = 6,02 \times 10^{23}\,mol^{-1}$
• Faraday's constant: $F = 96\,500\,C \cdot mol^{-1}$

Chemistry Formulae

• $n = \frac{m}{M}$
• $n = \frac{N}{N_A}$
• $c = \frac{n}{V} = \frac{m}{MV}$
• $n = \frac{V}{V_m}$
• $K_w = [H_3O^+][OH^-] = 1 \times 10^{-14} \text{ at } 25\,^{\circ}C$
• $\frac{c_a V_a}{c_b V_b} = \frac{n_a}{n_b}$
• $q = It = nF$
• $E^\theta_{cell} = E^\theta_{cathode} - E^\theta_{anode}$
• $E^\theta_{cell} = E^\theta_{oxidising\,agent} - E^\theta_{reducing\,agent}$

PHYSICS ASSESSMENT SYLLABUS DETAIL

Kinematics

• Vectors and Scalars: Vectors have magnitude and direction (e.g., force, velocity); scalars have magnitude only (e.g., distance, speed). Resultant vector is the single vector having the same effect as multiple vectors combined.
• Motion Terms: Position is a vector relative to a reference origin. Distance is scalar path length; displacement is vector change in position. Velocity is the rate of change of position (vector). Acceleration is the rate of change of velocity.
• Vertical Projectile Motion: Projectiles fall at $g = 9,8\,m \cdot s^{-2}$. Upward launch time to peak height equals fall time back to launch point (symmetry).
• Graphs: Gradient of position-time graph = velocity. Gradient of velocity-time graph = acceleration. Area under velocity-time graph = displacement.

Newton's Laws and Applications

• Weights and Forces: $F_g$ is Earth's pull on mass. Normal force ($F_N$) is perpendicular pull from a surface. Frictional force ($F_f$) opposes motion/tendency of motion.
• Newton's First Law: Objects stay at rest or in uniform velocity unless a net force acts. Defined by inertia.
• Newton's Second Law: $F_{net} = ma$. Acceleration is directly proportional to net force and inversely proportional to mass.
• Newton's Third Law: When A exerts force on B, B exerts equal and opposite force on A concurrently (Action-Reaction pairs).

Momentum, Impulse, Work, and Energy

• Linear Momentum: $p = mv$ (vector). Conservation of momentum applies to isolated systems (no external net forces).
• Impulse: $J = F_{net}\Delta t = \Delta p$. Used to explain safety features like airbags.
• Collisions: Elastic (conserves both momentum and kinetic energy); Inelastic (conserves only momentum).
• Work-Energy Theorem: Work done by net force equals change in kinetic energy ($W_{net} = \Delta E_k$).
• Conservation of Energy: Total mechanical energy ($E_k + E_p$) is constant in the absence of air resistance.

Electrodynamics, Fields, and Circuits

• Universal Gravitation: Force proportional to product of masses and inversely to distance squared ($r^2$).
• Electric Power: Measured in Watts ($1\,W = 1\,J \cdot s^{-1}$). Electrical energy unit: kilowatt-hour ($kWh$).
• Faraday's Law: Induced emf is proportional to the rate of change of magnetic flux linkage.
• Lenz's Law: Induced current direction creates a magnetic field that opposes the flux change.
• Rectification: Diodes allow current in one direction; bridge rectifiers (4 diodes) achieve full-wave rectification.

CHEMISTRY ASSESSMENT SYLLABUS DETAIL

Quantitative Chemistry

• Mole Concept: Mole is the SI unit for amount of substance. 1 mole = Avogadro's number of particles.
• Stoichiometry: Includes calculations for percentage yield ($\frac{\text{actual}}{\text{theoretical}} \times 100$) and percentage purity of samples.
• Polyatomic Ions (Memorization Required): Ammonium ($NH_4^+$), hydronium ($H_3O^+$), chlorate ($ClO_3^-$), ethanoate ($CH_3COO^-$), nitrate ($NO_3^-$), permanganate ($MnO_4^-$), carbonate ($CO_3^{2-}$), thiosulfate ($S_2O_3^{2-}$), dichromate ($Cr_2O_7^{2-}$).

Chemical Bonding and Intermolecular Forces

• Electronegativity: Tendency of an atom to attract bonding electrons. High difference leads to polar covalent or ionic bonds.
• Van der Waals Forces:
  • London Forces: Induced dipoles, present in all molecules (e.g., noble gases, hydrocarbons).
  • Dipole-Dipole: Between polar molecules.
  • Hydrogen Bonds: Special case of dipole-dipole; occurs when H is bonded to small, highly electronegative atoms ($N, O, F$) with lone pairs.
• Molecular Shapes: Linear ($CO_2$), angular ($H_2O$), trigonal planar ($BH_3$), tetrahedral ($CH_4$), trigonal pyramidal ($NH_3$).

Energy and Rates

• Activated Complex: High-energy, unstable transition state.
• Factors Affecting Rate: Surface area, concentration, pressure (gases), temperature, and catalysts. Catalysts lower activation energy by providing an alternative pathway.
• Maxwell-Boltzmann Distribution: Graphic representation showing the distribution of kinetic energies among particles.

Equilibrium and Acids/Bases

• Le Châtelier's Principle: Systems in equilibrium counteract external stress (changes in concentration, pressure, temperature).
• Lowry-Brønsted Model: Acid is a proton ($H^+$) donor; Base is a proton acceptor.
• Strong vs. Weak Acids: Strong ($HCl, H_2SO_4, HNO_3$) ionise completely; weak ones ($CH_3COOH, (COOH)_2$) ionise partially.
• Amphoteric Substances: Can act as both acid and base (e.g., $H_2O, HCO_3^-$).

Electrochemistry and Organic Chemistry

• Galvanic Cells: Convert chemical energy to electrical energy via spontaneous redox reactions. Notation: Anode (Oxidation) on left || Cathode (Reduction) on right.
• Electrolysis: Uses electrical energy for non-spontaneous reactions (e.g., electroplating, refining copper, chlor-alkali industry).
• Organic Homologous Series: Alkanes (saturated), alkenes (unsaturated double bond), haloalkanes, alcohols (hydroxyl), carboxylic acids (carboxyl), esters.
• Isomerism: Compounds with same molecular formula but different structural formulas (Chain, Positional, Functional). Example: Propanoic acid and ethyl methanoate are functional isomers.
• Reactions:
  • Substitution (Alkanes to haloalkanes via UV light).
  • Addition (Hydrogenation, Hydration, Halogenation of alkenes).
  • Elimination (Dehydrohalogenation, Cracking, Dehydration).
  • Esterification (Acid-catalysed reaction between alcohol and carboxylic acid).

SCIENTIFIC SKILLS

• Arithmetic: Use of scientific notation, Reciprocals, $n^{th}$-roots, Sines, Cosines, Tangents. Pythagoras' Theorem and solving simultaneous/quadratic equations.
• Conversions: Metric scales from pico ($10^{-12}$) to giga ($10^9$).
• Graphing: Identifying variables (Independent vs. Dependent). Determining gradient ($\frac{\Delta y}{\Delta x}$) and area significance. Relationships: direct proportion, inverse proportion ($y \propto \frac{1}{x}$), and square proportionality ($y \propto x^2$).
• Practical Skills: Designing controlled experiments, distinguishing between precision (closeness of results) and accuracy (closeness to true value), and identifying bias/error.