Grade 10: Science

In this unit, 'Chemistry: chemical reactions and equations', you learn to balance equations and classify reactions. You work with notes, a worked line and a self-mark. You see it, say it, then do it alone.

• Observe: see, touch, measure or watch a safe demonstration linked to 'Chemistry: chemical reactions and equations' and write what you notice.
• Explain: use the key words of the unit to say what is happening and why, in a few lines.
• Use it: balance equations and classify reactions. Use a diagram, table or short calculation where it fits.
• Test and conclude: say what evidence supports your answer and what you would change.

Step by step.

1. Step 1, Balance iron plus steam: Fe + H2O gives Fe3O4 + H2. Fix Fe first with 3Fe. Fe3O4 has 4 oxygen, so use 4H2O. Then hydrogen gives 4H2. Final: 3Fe + 4H2O gives Fe3O4 + 4H2, with 3 Fe, 8 H and 4 O on each side.
2. Step 2, Balance aluminium and hydrochloric acid: Al + HCl gives AlCl3 + H2. Use 2Al to give 2AlCl3, which needs 6HCl and gives 3H2. Final: 2Al + 6HCl gives 2AlCl3 + 3H2. Check: 2 Al, 6 H, 6 Cl both sides.
3. Step 3, Classify. 2Mg + O2 gives 2MgO is combination and also oxidation. CaCO3 gives CaO + CO2 on heating is decomposition (thermal). Zn + CuSO4 gives ZnSO4 + Cu is displacement. AgNO3 + NaCl gives AgCl + NaNO3 is double displacement.
4. Step 4, Identify observations. The silver chloride in the last reaction is a white precipitate, so add (s) state symbols: AgNO3(aq) + NaCl(aq) gives AgCl(s) + NaNO3(aq). Zinc displaces copper because zinc is more reactive; blue solution fades.
5. Step 5, Identify oxidation and reduction in CuO + H2 gives Cu + H2O. CuO loses oxygen so it is reduced; H2 gains oxygen so it is oxidised. Together a redox reaction. Rancidity and corrosion are everyday oxidations.
6. Step 6, Your turn: balance Fe2O3 + CO gives Fe + CO2 and name the type. Answer: Fe2O3 + 3CO gives 2Fe + 3CO2; it is a redox reaction.

Activity. About 30 to 40 minutes of class work, then one short practice task for home. Keep evidence: a worked task and a corrected copy.

Standard to meet. Balance equations and classify reactions: at least 8 of 10 marks on a short task, with one line of reasoning for each answer.

In this unit, 'Chemistry: acids, bases and salts', you learn to use pH and describe common salts. You work with notes, a worked line and a self-mark. You see it, say it, then do it alone.

• Observe: see, touch, measure or watch a safe demonstration linked to 'Chemistry: acids, bases and salts' and write what you notice.
• Explain: use the key words of the unit to say what is happening and why, in a few lines.
• Use it: use pH and describe common salts. Use a diagram, table or short calculation where it fits.
• Test and conclude: say what evidence supports your answer and what you would change.

Step by step.

1. Step 1, Use indicators to sort acids from bases. Blue litmus turns red in acid, red litmus turns blue in base. Phenolphthalein is colourless in acid and pink in base, and methyl orange is red in acid and yellow in base. Red cabbage juice also works. Wear goggles, use dilute solutions and never taste lab chemicals.
2. Step 2, Use the pH scale, where pH = -log10 of the hydrogen ion concentration. For 0.001 mol/L HCl, the concentration is 10^-3, so pH = 3. For 0.01 mol/L NaOH, pOH = 2 and pH = 14 - 2 = 12. Neutral water is 7. Each step of 1 means a tenfold change, so pH 3 is 100 times more acidic than pH 5.
3. Step 3, Write neutralisation: HCl + NaOH gives NaCl + H2O. Atoms balance: 2 H, 1 Cl, 1 Na and 1 O on each side. 25 mL of 0.10 mol/L HCl holds 0.0025 mol, so it needs 0.0025 mol NaOH, which is 25 mL of 0.10 mol/L NaOH. An antacid works the same way against stomach acid.
4. Step 4, Predict a salt's nature. Strong acid with strong base, like NaCl, gives a neutral salt. Strong acid with weak base, like ammonium chloride, gives an acidic solution. Weak acid with strong base, like sodium carbonate, gives a basic solution. Electrolysing brine, NaCl solution, makes NaOH, chlorine and hydrogen.
5. Step 5, Describe four common salts. Baking soda NaHCO3 is a mild base used in baking and antacids. On heating, 2NaHCO3 gives Na2CO3 + H2O + CO2. Washing soda is Na2CO3 with water of crystallisation. Bleaching powder CaOCl2 disinfects water. Plaster of Paris, CaSO4 with half a water molecule, sets hard when mixed with water.
6. Step 6, Your turn: find the pH of 0.0001 mol/L HCl and say whether it is acidic or basic. Answer: the concentration is 10^-4, so pH = 4. It is acidic, and it is 10 times more acidic than a pH 5 solution.

Activity. About 30 to 40 minutes of class work, then one short practice task for home. Keep evidence: a worked task and a corrected copy.

Standard to meet. Use pH and describe common salts: at least 8 of 10 marks on a short task, with one line of reasoning for each answer.

In this unit, 'Chemistry: metals, non-metals and carbon compounds', you learn to explain reactivity and bonding in carbon compounds. You work with notes, a worked line and a self-mark. You see it, say it, then do it alone.

• Observe: see, touch, measure or watch a safe demonstration linked to 'Chemistry: metals, non-metals and carbon compounds' and write what you notice.
• Explain: use the key words of the unit to say what is happening and why, in a few lines.
• Use it: explain reactivity and bonding in carbon compounds. Use a diagram, table or short calculation where it fits.
• Test and conclude: say what evidence supports your answer and what you would change.

Step by step.

1. Step 1, Use the reactivity series K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Ag, Au. Predict: iron plus copper sulphate reacts (Fe is above Cu): Fe + CuSO4 gives FeSO4 + Cu. Copper plus zinc sulphate does not react.
2. Step 2, Explain ionic bonding in NaCl. Na (2,8,1) loses one electron to become Na+ (2,8); Cl (2,8,7) gains it to become Cl- (2,8,8). Opposite charges attract. Ionic solids have high melting points (801 C) and conduct when molten or dissolved.
3. Step 3, Explain covalent bonding in methane CH4. Carbon (2,4) shares one electron pair with each of four hydrogens, completing its octet. Covalent compounds have low melting points and are poor conductors.
4. Step 4, Name carbon compounds. Alkanes CnH2n+2: methane CH4, ethane C2H6, propane C3H8. Alkene C2H4 is ethene with a double bond. Ethanol C2H5OH has an alcohol group. Ethanoic acid CH3COOH has a carboxylic acid group.
5. Step 5, Write reactions. Combustion: CH4 + 2O2 gives CO2 + 2H2O. Esterification: CH3COOH + C2H5OH with acid catalyst gives ethyl ethanoate, fruity smelling, + H2O. Saponification of oils with NaOH gives soap.
6. Step 6, Your turn: give the formula of the alkane with 5 carbons and say if Cu displaces Zn from ZnSO4. Answer: C5H12; no, copper is less reactive than zinc.

Activity. About 30 to 40 minutes of class work, then one short practice task for home. Keep evidence: a worked task and a corrected copy.

Standard to meet. Explain reactivity and bonding in carbon compounds: at least 8 of 10 marks on a short task, with one line of reasoning for each answer.

In this unit, 'Physics: light, reflection and refraction', you learn to use mirror and lens formulae. You work with notes, a worked line and a self-mark. You see it, say it, then do it alone.

• Observe: see, touch, measure or watch a safe demonstration linked to 'Physics: light, reflection and refraction' and write what you notice.
• Explain: use the key words of the unit to say what is happening and why, in a few lines.
• Use it: use mirror and lens formulae. Use a diagram, table or short calculation where it fits.
• Test and conclude: say what evidence supports your answer and what you would change.

Step by step.

1. Step 1, Use the laws of reflection: the angle of incidence equals the angle of reflection, and both rays and the normal lie in one plane. Use the sign convention: distances are measured from the pole, positive in the direction of incident light. A concave mirror has negative f. Never look at the Sun in a mirror or lens.
2. Step 2, Apply the mirror formula 1/v + 1/u = 1/f. A concave mirror has f = -15 cm and an object is placed at u = -30 cm. Then 1/v = -1/15 + 1/30 = -1/30, so v = -30 cm. The image forms at the same distance, in front of the mirror, as the object sits at the centre of curvature.
3. Step 3, Find magnification, m = -v/u. In step 2, m = -(-30)/(-30) = -1, so the image is real, inverted and the same size. Move the object to u = -10 cm inside the focus: 1/v = -1/15 + 1/10 = 1/30, so v = +30 cm behind the mirror and m = +3, a magnified, upright, virtual image. This is how a shaving mirror works.
4. Step 4, Use refraction. Snell's law gives n = sin i / sin r. Light enters glass of n = 1.5 at i = 30 degrees: sin r = 0.5 / 1.5 = 0.333, so r is about 19.5 degrees, bending towards the normal. The speed in glass is 3 x 10^8 / 1.5 = 2 x 10^8 m/s. Never aim a laser pointer at anyone's eyes.
5. Step 5, Use the lens formula 1/v - 1/u = 1/f. A convex lens has f = +20 cm and an object at u = -40 cm: 1/v = 1/20 - 1/40 = 1/40, so v = +40 cm and m = v/u = -1. Power P = 1/f in metres, so P = 1/0.20 = +5 D. A concave lens with f = -25 cm has P = -4 D.
6. Step 6, Your turn: a concave mirror has f = -10 cm and the object is at u = -30 cm. Find v and m, and describe the image. Answer: 1/v = -1/10 + 1/30 = -1/15, so v = -15 cm; m = -(-15)/(-30) = -0.5. The image is real, inverted and diminished, in front of the mirror.

Activity. About 30 to 40 minutes of class work, then one short practice task for home. Keep evidence: a worked task and a corrected copy.

Standard to meet. Use mirror and lens formulae: at least 8 of 10 marks on a short task, with one line of reasoning for each answer.

In this unit, 'Physics: electricity and magnetic effects of current', you learn to apply Ohm's law and describe motors and generators. You work with notes, a worked line and a self-mark. You see it, say it, then do it alone.

• Observe: see, touch, measure or watch a safe demonstration linked to 'Physics: electricity and magnetic effects of current' and write what you notice.
• Explain: use the key words of the unit to say what is happening and why, in a few lines.
• Use it: apply Ohm's law and describe motors and generators. Use a diagram, table or short calculation where it fits.
• Test and conclude: say what evidence supports your answer and what you would change.

Step by step.

1. Step 1, Apply V = IR. A nichrome wire has a 6 V cell across it and a measured current of 0.3 A. R = V / I = 6 / 0.3 = 20 ohm. Doubling the voltage to 12 V gives 0.6 A, since resistance is constant.
2. Step 2, Combine resistors. Series 10 ohm and 20 ohm give 30 ohm. In parallel, 1/R = 1/10 + 1/20 = 3/20, so R = 6.67 ohm. With 6 V, series current is 0.2 A and parallel total current is 0.9 A.
3. Step 3, Use power and heat. P = V I. A heater at 220 V draws 5 A, so P = 1100 W. In 2 hours it uses 1.1 kW x 2 = 2.2 kWh. Joule heating H = I^2 R t.
4. Step 4, Describe magnetic effects. A current in a wire gives a circular field, found by the right-hand rule. A solenoid acts as a bar magnet. Force on a conductor follows Fleming's left-hand rule: thumb force, first finger field, second finger current.
5. Step 5, Explain the motor and generator. An electric motor turns a coil in a field using a split-ring commutator to reverse current every half turn. A generator turns a coil in a field to induce current by electromagnetic induction, shown by Fleming's right-hand rule.
6. Step 6, Your turn: a 40 ohm bulb is across 220 V. Find current and power. Answer: I = 220/40 = 5.5 A; P = 220 x 5.5 = 1210 W.

Activity. About 30 to 40 minutes of class work, then one short practice task for home. Keep evidence: a worked task and a corrected copy.

Standard to meet. Apply Ohm's law and describe motors and generators: at least 8 of 10 marks on a short task, with one line of reasoning for each answer.

In this unit, 'Biology: life processes and control and coordination', you learn to describe nutrition, transport, nervous and hormonal control. You work with notes, a worked line and a self-mark. You see it, say it, then do it alone.

• Observe: see, touch, measure or watch a safe demonstration linked to 'Biology: life processes and control and coordination' and write what you notice.
• Explain: use the key words of the unit to say what is happening and why, in a few lines.
• Use it: describe nutrition, transport, nervous and hormonal control. Use a diagram, table or short calculation where it fits.
• Test and conclude: say what evidence supports your answer and what you would change.

Step by step.

1. Step 1, Describe nutrition. In photosynthesis, 6CO2 + 6H2O gives C6H12O6 + 6O2 using light and chlorophyll, with gases entering through stomata. Humans digest food: amylase in saliva starts on starch, pepsin with hydrochloric acid works in the stomach, bile and pancreatic juice act in the small intestine, and villi absorb the nutrients. For the leaf starch test, warm ethanol only in a water bath, never over a flame.
2. Step 2, Describe respiration. Aerobic respiration: glucose + oxygen gives carbon dioxide + water + energy. Without oxygen, yeast makes ethanol and carbon dioxide, and tired muscle makes lactic acid. Energy is stored in ATP. This explains why breathing and heart rate rise during exercise, so check your own pulse safely after light activity.
3. Step 3, Describe transport. The human heart has four chambers and double circulation: blood goes to the lungs and back, then around the body. At 72 beats a minute with 70 mL pumped per beat, the heart moves 72 x 70 = 5,040 mL, about 5 litres, a minute and beats 103,680 times a day. In plants, xylem carries water upward and phloem carries food.
4. Step 4, Describe nervous control. A neuron has dendrites, a cell body and an axon. In a reflex arc touching something hot sends an impulse along a sensory neuron to the spinal cord, then along a motor neuron to the arm muscle. Suppose an impulse travels at 100 m/s. A 0.6 m path takes only 0.006 s. The brain's cerebrum thinks, the cerebellum balances, the medulla controls breathing.
5. Step 5, Describe hormones. Insulin from the pancreas lowers blood sugar, thyroxine from the thyroid needs iodine, adrenaline prepares for danger, and growth hormone helps growth. Feedback works like a thermostat: after a meal, blood sugar rises, insulin is released, sugar falls to its normal range, and release stops. In plants, auxin makes shoots bend toward light.
6. Step 6, Your turn: trace a reflex when a hand touches a hot cup, and name the hormone that lowers blood sugar. Answer: receptor in skin, sensory neuron, spinal cord, motor neuron, muscle which pulls the hand away. The hormone is insulin.

Activity. About 30 to 40 minutes of class work, then one short practice task for home. Keep evidence: a worked task and a corrected copy.

Standard to meet. Describe nutrition, transport, nervous and hormonal control: at least 8 of 10 marks on a short task, with one line of reasoning for each answer.

In this unit, 'Biology: reproduction, heredity and evolution', you learn to describe reproduction and Mendel's laws. You work with notes, a worked line and a self-mark. You see it, say it, then do it alone.

• Observe: see, touch, measure or watch a safe demonstration linked to 'Biology: reproduction, heredity and evolution' and write what you notice.
• Explain: use the key words of the unit to say what is happening and why, in a few lines.
• Use it: describe reproduction and Mendel's laws. Use a diagram, table or short calculation where it fits.
• Test and conclude: say what evidence supports your answer and what you would change.

Step by step.

1. Step 1, Compare reproduction. Asexual: binary fission in amoeba, budding in yeast, fragmentation in Spirogyra, vegetative propagation by cuttings. Sexual reproduction involves two gametes and gives variation.
2. Step 2, Trace human reproduction: sperm from testes meet an egg in the fallopian tube, fertilisation forms a zygote that divides and implants in the uterus, the placenta supplies nutrients, and about 9 months later birth occurs.
3. Step 3, Do a monohybrid cross. Tall (T) is dominant over dwarf (t). Cross Tt x Tt: gametes T, t and T, t give TT, Tt, Tt, tt. Phenotype ratio 3 tall to 1 dwarf, genotype ratio 1:2:1.
4. Step 4, Do a dihybrid cross. Round yellow RRYY x wrinkled green rryy gives all RrYy. Selfing gives 9 round yellow, 3 round green, 3 wrinkled yellow, 1 wrinkled green. From 160 plants expect 90, 30, 30 and 10.
5. Step 5, Explain sex determination. Humans have 22 pairs of autosomes plus XX or XY. The egg always carries X. The sperm carries X or Y, so the child's sex is decided by the father's sperm with a 50 per cent chance each.
6. Step 6, Your turn: cross heterozygous tall Tt with dwarf tt and give the ratio. Answer: Tt, Tt, tt, tt, so 1 tall to 1 dwarf.

Activity. About 30 to 40 minutes of class work, then one short practice task for home. Keep evidence: a worked task and a corrected copy.

Standard to meet. Describe reproduction and Mendel's laws: at least 8 of 10 marks on a short task, with one line of reasoning for each answer.

In this unit, 'Environment and sustainable use of resources', you learn to analyse ecosystems and sustainable resource use. You work with notes, a worked line and a self-mark. You see it, say it, then do it alone.

• Observe: see, touch, measure or watch a safe demonstration linked to 'Environment and sustainable use of resources' and write what you notice.
• Explain: use the key words of the unit to say what is happening and why, in a few lines.
• Use it: analyse ecosystems and sustainable resource use. Use a diagram, table or short calculation where it fits.
• Test and conclude: say what evidence supports your answer and what you would change.

Step by step.

1. Step 1, Build a food chain. Grass, grasshopper, frog, snake, eagle. Name the producer (grass), primary consumer (grasshopper), secondary consumer (frog), tertiary consumer (snake) and quaternary, top consumer (eagle). Add decomposers like bacteria.
2. Step 2, Apply the 10 per cent law. If grass captures 10,000 J, the grasshopper gets 1000 J, the frog 100 J, the snake 10 J and the eagle 1 J. Hence food chains are short, usually 3 to 5 levels.
3. Step 3, Analyse waste. Biodegradable waste like vegetable peels is broken down by microbes. Non-biodegradable waste like plastic stays. Biomagnification: a pesticide at 0.02 ppm in water can reach much higher levels in top predators.
4. Step 4, Discuss the ozone layer. UV breaks O2 and O3 in the stratosphere. Chlorofluorocarbons release chlorine atoms which destroy ozone, so their use was curbed. Ozone absorbs harmful UV.
5. Step 5, Plan resource use. Use the 3 Rs, rainwater harvesting, and water management. Compare coal and petroleum as non-renewable fossil fuels with solar and wind as renewable. Use CNG to cut air pollution.
6. Step 6, Your turn: a producer fixes 5000 J. How much reaches the tertiary consumer by the 10 per cent law? Answer: 5000 to 500 to 50 to 5 J, so 5 J.

Activity. About 30 to 40 minutes of class work, then one short practice task for home. Keep evidence: a worked task and a corrected copy.

Standard to meet. Analyse ecosystems and sustainable resource use: at least 8 of 10 marks on a short task, with one line of reasoning for each answer.

On the slide: L1 Basic · Using my five senses

Notes: Name the five senses and use them to describe a safe object. Notes: place a leaf, a smooth stone and a soft cloth in a bag; learners touch and describe each. Never taste or smell unknown things; teach children to ask first. Grades 1 and 2.

On the slide: L2 Awareness · Fair tests

Notes: Describe a fair test by naming what is changed, what is measured and what stays the same. Notes: plant two seed pots, one in light and one in the dark, with equal water and soil. Learners say the one changed factor, and draw both pots after a week. Grades 3 and 4.

On the slide: L3 Foundation · Measuring and recording

Notes: Measure length, mass, time and temperature and record them in a table. Notes: a plant grows 2 cm in 4 days, which is 0.5 cm a day. Learners take three readings of 12, 14 and 13 mm, find the mean of 13, and say why repeats help. Grades 5 and 6.

On the slide: L4 Practitioner · Variables, graphs and density

Notes: Apply a formula and draw a graph from a fair test. Notes: density equals mass over volume; a metal block of 54 g and 20 cm3 has density 2.7 g/cm3. Learners plot mass against volume for three blocks and read the gradient. Dry the benchtop before using water. Grades 7 and 8.

This course: Grade 10 Science is at this level. Its units include Chemistry: chemical reactions and equations; Chemistry: acids, bases and salts; Chemistry: metals, non-metals and carbon compounds; Physics: light, reflection and refraction and more.

On the slide: L5 Specialist · Evidence, anomalies and models

Notes: Analyse data, spot an anomaly and judge how well a model fits the evidence. Notes: readings of 5.1, 5.3, 5.2 and 7.9 hold one anomaly at 7.9, so the mean of the rest is 5.2. Learners suggest a cause, repeat the trial and write a conclusion that cites the numbers. Grades 9 and 10.

On the slide: L6 Advanced · Modelling and curve fitting

Notes: Apply least-squares fitting and error reasoning to link data to a model. Notes: the points (1,2.1), (2,3.9), (3,6.2), (4,7.8), (5,10.1) give slope 1.99 and intercept 0.05, with R squared 0.997. Learners explain what the intercept means and whether a straight line is right.

On the slide: L7 Super expert · Study design and sample size

Notes: Evaluate and create a study with a clear hypothesis, controls, sample size and ethics approval. Notes: to detect a 5-unit difference with spread 10 at 5 per cent significance and 80 per cent power needs about 63 per group. Learners write a pre-registered plan and list the risks and consent steps.