Companion PDF worksheet for Edexcel IGCSE Biology Lecture 49 - Ecosystems. Contains short answer questions, an activity requiring lateral thinking and exam-style questions. Specification Point 4.1 - Understand the terms population, community, habitat and ecosystem. Specification Point 4.2 - Practical: investigate the population size of an organism in two different areas using quadrats. Complete set of Chapter 6 Worksheets are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 1.2 - Understand how river landscapes change over the course of a river, with distinctive upland and lowland landforms, including the formation of valleys, interlocking spurs, waterfalls, meanders, oxbow lakes, floodplains and levees. Complete set of Chapter 1 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 5.1 - Understand the distributions and characteristics of the world’s biomes (tropical, temperate and boreal forests, tropical and temperate grasslands, deserts and tundra). Complete set of Chapter 6 Lectures are available.

Companion PDF worksheet for Edexcel IGCSE Chemistry Lecture 13 - Covalent Bonding. Contains short answer questions, an activity requiring lateral thinking and exam-style questions. Specification Point 1.44 - Know that a covalent bond is formed between atoms by the sharing of a pair of electrons. Specification Point 1.45 - Understand covalent bonds in terms of electrostatic attractions. Specification Point 1.46 - Understand how to use dot-and-cross diagrams to represent covalent bonds in a variety of molecules. Specification Point 1.47 - Explain why substances with a simple molecular structures are gases or liquids, or solids with low melting and boiling points. Specification Point 1.48 - Explain why the melting and boiling points of substances with simple molecular structures increase, in general, with increasing relative molecular mass. Specification Point 1.49 - Explain why substances with giant covalent structures are solids with high melting and boiling points. Specification Point 1.50 - Explain how the structures of diamond, graphite and fullerene influence their physical properties, including electrical conductivity and hardness. Specification Point 1.51 - Know that covalent compounds do not usually conduct electricity. Complete set of Chapter 3 Worksheets are available.

Companion PDF worksheet for Edexcel IGCSE Chemistry Lecture 3 - Calculating Solubility. Contains short answer questions, an activity requiring lateral thinking and exam-style questions. Specification Point 1.5C - Know what is meant by the term solubility in the units grams per 100 grams of solvent. Specification Point 1.6C - Understand how to plot and interpret solubility curves. Specification Point 1.7C - Practical: investigate the solubility of a solid in water at a specific temperature. Complete set of Chapter 1 Worksheets are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 3.7.1 - Inheritance. Complete set of Chapter 7 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 3.7.4 - Populations in ecosystems. Complete set of Chapter 7 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 1.1 - Understand the three states of matter in terms of the arrangement, movement & energy of the particles. Specification Point 1.2 - Understand the interconversions between the three states of matter in terms of: The names of the interconversions. How they are achieved. The changes in arrangement, movement & energy of the particles. Complete set of Chapter 1 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 5.12 - Understand how restriction enzymes are used to cut DNA at specific sites and ligase enzymes are used to join pieces of DNA together. Specification Point 5.13 - Understand how plasmids and viruses can act as vectors, which take up pieces of DNA, and then insert this recombinant DNA into other cells. Specification Point 5.14 - Understand how large amounts of human insulin can be manufactured from genetically modified bacteria that are grown in a fermenter. Specification Point 5.15 - Understand how genetically modified plants can be used to improve food production. Specification Point 5.16 - Understand that the term transgenic means the transfer of genetic material from one species to a different species. Complete set of Chapter 7 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 3.22 - Understand that most phenotypic features are the result of polygenic inheritance rather than single genes. Specification Point 3.23 - Describe patterns of monohybrid inheritance using a genetic diagram. Specification Point 3.24 - Understand how to interpret family pedigrees. Specification Point 3.25 - Predict probabilities of outcomes from monohybrid crosses. Specification Point 3.26 - Understand how the sex of a person is controlled by one pair of chromosomes, XX in a female and XY in a male. Specification Point 3.27 - Describe the determination of the sex of offspring at fertilisation, using a genetic diagram. Complete set of Chapter 5 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 3.1 - Know that chemical reactions in which heat energy is given out are described as exothermic, and those in which heat energy is taken in are described as endothermic. Specification Point 3.2 - Describe simple calorimetry experiments for reactions such as combustion, displacement, dissolving and neutralisation. Specification Point 3.3 - Calculate the heat energy change from a measured temperature change using the expression Q = mcΔT. Specification Point 3.4 - Calculate the molar enthalpy change (ΔH) from the heat energy change, Q. Specification Point 3.8 - Practical: investigate temperature changes accompanying some of the following types of change: salts dissolving in water, neutralisation reactions, displacement reactions and combustion reactions. Complete set of Chapter 6 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 4.7.3.6 - Maintaining biodiversity. Complete set of Chapter 7 Lectures are available.

Companion PDF worksheet for Edexcel IGCSE Biology Lecture 31 - Coordination in Humans. Contains short answer questions, an activity requiring lateral thinking and exam-style questions. Specification Point 2.86 - Describe how nervous and hormonal communication control responses and understand the differences between the two systems. Specification Point 2.87 - Understand that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves. Specification Point 2.88 - Understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses. Specification Point 2.89 - Understand the role of neurotransmitters at synapses. Complete set of Chapter 4 Worksheets are available.

Companion PDF worksheet for Edexcel IGCSE Biology Lecture 59 - Fish Farming. Contains short answer questions, an activity requiring lateral thinking and exam-style questions. Specification Point 5.9B - Understand the methods used to farm large numbers of fish to provide a source of protein, including maintaining water quality, controlling intraspecific and interspecific predation, controlling disease, removing waste products, controlling the quality and frequency of feeding, and selective breeding. Complete set of Chapter 7 Worksheets are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 1.5C - Know what is meant by the term solubility in the units grams per 100 grams of solvent. Specification Point 1.6C - Understand how to plot and interpret solubility curves. Specification Point 1.7C - Practical: investigate the solubility of a solid in water at a specific temperature. Complete set of Chapter 1 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 3.1.2 - Memory. Factors affecting the accuracy of eyewitness testimony: misleading information, including leading questions and post-event discussion; anxiety. Improving the accuracy of eyewitness testimony, including the use of the cognitive interview. Complete set of Chapter 2 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 2.55B -Understand how water is absorbed by root hair cells. Specification Point 2.56B -Understand that transpiration is the evaporation of water from the surface of a plant. Specification Point 2.57B -Understand how the rate of transpiration is affected by changes in humidity, wind speed, temperature and light intensity. Specification Point 2.58B - Practical: investigate the role of environmental factors in determining the rate of transpiration from a leafy shoot. Complete set of Chapter 3 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 4.6.1.5 - DNA structure. Complete set of Chapter 6 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 3.1 - Understand the causes of tropical cyclone hazards, including ocean temperature, atmospheric pressure, wind shear and Coriolis force. Specification Point 3.1 - Understand the causes of volcanic and earthquake hazards, including the role of plate boundaries and hotspots. Complete set of Chapter 3 Lectures are available.

Powerpoint lecture covering the following in a modern, concise format: Specification Point 4.2.1 - Approaches in psychology. The psychodynamic approach: the role of the unconscious, the structure of personality, that is Id, Ego and Superego, defence mechanisms including repression, denial and displacement, psychosexual stages. Complete set of Chapter 5 Lectures are available.