Guided lessons
Chemistry, Physics, Biology, Mathematics and Agriculture
- Chemistry · Bonding & structure · 8 min
Why water is polar
Explain how bond polarity and a bent shape make water a polar molecule.
- Physics · 5 steps · 7 min
Magnetic field lines
Trace magnetic field lines and describe their direction around a bar magnet.
- Biology · 6 steps · 10 min
Inside a plant cell
Identify the main organelles of a plant cell and state the function of each.
- Mathematics · 4 steps · 6 min
Platonic solids: the cube
Count the faces, edges and vertices of a cube and verify Euler’s formula.
- Agriculture · 6 steps · 8 min
How a stem transports
Identify the tissues in a dicot stem and describe how water and food are transported.
- Chemistry · Atomic structure · 8 min
Oxygen-16 Atom
Connect atomic number 8, mass number 16 and six valence electrons.
- Chemistry · Atomic structure · 8 min
Sodium-23 Atom
Explain why sodium readily loses its single outer electron.
- Chemistry · Atomic structure · 8 min
Magnesium-24 Atom
Use valence electrons to predict formation of Mg²⁺.
- Chemistry · Atomic structure · 8 min
Sodium Ion (Na⁺)
Distinguish electron loss from a change in atomic number.
- Chemistry · Atomic structure · 8 min
Fluoride Ion (F⁻)
Explain how gaining an electron forms a negative ion.
- Chemistry · Atomic structure · 8 min
Chlorine Isotopes
Compare isotopes using proton and neutron counts.
- Chemistry · Bonding & structure · 8 min
Hydrogen Molecule
Identify a non-polar single covalent bond.
- Chemistry · Bonding & structure · 8 min
Oxygen Molecule
Identify the double covalent bond in O₂.
- Chemistry · Bonding & structure · 8 min
Nitrogen Molecule
Relate the triple bond in N₂ to its low reactivity.
- Chemistry · Bonding & structure · 8 min
Hydrogen Chloride
Distinguish polar covalent HCl from its ions in aqueous hydrochloric acid.
- Chemistry · Bonding & structure · 8 min
Ammonia Molecule
Explain how one lone pair gives ammonia a pyramidal shape.
- Chemistry · Bonding & structure · 8 min
Carbon Dioxide Molecule
Explain why two polar bonds cancel in linear carbon dioxide.
- Chemistry · Organic chemistry · 8 min
Ethane Molecule
Recognise a saturated alkane with tetrahedral carbon centres.
- Chemistry · Organic chemistry · 8 min
Ethene Molecule
Identify the double bond and explain addition reactions.
- Chemistry · Organic chemistry · 8 min
Ethyne Molecule
Identify the triple bond of an alkyne.
- Chemistry · Organic chemistry · 8 min
Ethanol Molecule
Locate the hydroxyl group and distinguish an alcohol from an acid.
- Chemistry · Organic chemistry · 8 min
Ethanoic Acid Molecule
Identify a carboxyl group and explain weak-acid ionisation.
- Chemistry · Organic chemistry · 8 min
Ethyl Ethanoate Molecule
Identify the ester linkage and products of esterification.
- Chemistry · Bonding & structure · 8 min
Diamond Structure
Link diamond’s giant covalent structure to hardness and electrical insulation.
- Chemistry · Bonding & structure · 8 min
Graphite Layers
Explain why graphite conducts electricity and acts as a lubricant.
- Chemistry · Bonding & structure · 8 min
Metallic Bonding in Copper
Explain electrical conduction and metallic bonding.
- Chemistry · Organic chemistry · 8 min
Poly(ethene) Chain
Connect an ethene monomer to an addition-polymer repeat unit.
- Chemistry · Organic chemistry · 8 min
Soap Micelle
Explain how soap disperses grease in water.
- Chemistry · Reactions & states · 8 min
Particle States of Matter
Compare particle arrangements and explain changes of state.
- Chemistry · Reactions & states · 8 min
Acid–Base Neutralisation
Identify the net ionic change and distinguish spectator ions.
- Chemistry · Reactions & states · 8 min
Silver Chloride Precipitation
Recognise an insoluble precipitate and identify spectator ions.
- Chemistry · Practical chemistry · 8 min
Filtration Apparatus
Choose filtration for an insoluble solid–liquid mixture.
- Chemistry · Practical chemistry · 8 min
Simple Distillation Apparatus
Trace solvent separation and explain the condenser’s role.
- Chemistry · Practical chemistry · 8 min
Acid–Base Titration Setup
Identify volumetric apparatus and distinguish endpoint from equivalence.
- Chemistry · Practical chemistry · 8 min
Paper Chromatography
Explain separation and calculate an Rf value.
- Chemistry · Practical chemistry · 8 min
Electrolysis of Brine
Identify oxidation at the anode and reduction at the cathode.
- Chemistry · Practical chemistry · 8 min
Daniell Cell
Trace electrons and ions in a galvanic cell.
- Chemistry · Practical chemistry · 8 min
Copper Electroplating
Identify the electrode to be coated and the reduction reaction.
- Chemistry · Industrial chemistry · 8 min
Haber Process
Apply dynamic equilibrium to industrial ammonia manufacture.
- Chemistry · Industrial chemistry · 8 min
Contact Process
Trace sulfuric acid manufacture and identify the catalyst.
- Chemistry · Industrial chemistry · 8 min
Crude Oil Fractionation
Relate chain length and boiling range to fraction collection.
- Chemistry · Bonding & structure · 8 min
Methane and tetrahedral bonding
Relate four shared pairs to tetrahedral geometry.
- Chemistry · Bonding & structure · 8 min
Why salt forms a lattice
Distinguish formula units from molecules and explain ionic conduction.
- Chemistry · Atomic structure · 8 min
Atomic number and mass number
Distinguish proton number, neutron number and electron arrangement.