Science at key stage 3    (Year 8)

• that rocks are usually made up of a mixture of mineral grains
• that two main textures can be recognised
• how to use experimental evidence and models to explain the texture of different rocks

• that rocks at the Earth's surface disintegrate through exposure to water in the environment, which causes chemical reactions
• how to record results over a period of time
• to use knowledge and understanding of the composition of igneous rocks to explain results of changes over time

• that rocks are broken down by forces that result from stresses generated when water in cracks and fissures expands on freezing
• that rocks at the Earth's surface are broken down by forces that result from stresses generated when rocks expand and contract on heating and cooling

• to relate a landscape to a process of weathering

• that rock fragments become sediment grains which can be transported by water currents and deposited when the energy is dissipated
• to make predictions about where sediment is deposited

• how to frame a question that can be investigated
• to decide whether evidence supports predictions
• that larger grains are not taken as far, as it requires more energy to move them
• that sediment grains of similar size are deposited together

• that as transportation times and distances increase, sediment grains become more rounded and are also sorted into similar sizes
• to present data in an appropriate form

• about fragmentation and transportation

• that sedimentary layers are the result of distinct episodes of sedimentation over a variety of timescales
• to suggest explanations for observations they make

• that sedimentary layers can be formed by the evaporation of waters containing dissolved salts
• that the remains of dead organisms and their shelly material can accumulate to form sediments
• to use evidence in rock layers to suggest a sequence of events over time
• about the use of fossils as evidence

• to relate key ideas about geological changes to each other