Science at key stage 3    (Year 8)

• Review what pupils recall from previous work on living things in the environment by providing stimulus pictures of different habitats and asking pupils to suggest what types of animal and plant live there. Ask pupils to suggest reasons why the animals and plants differ, focusing on environmental factors. Use the opportunity to encourage pupils to think about how organisms get all the things they need to survive in these habitats.

• Remind pupils of the work they did in year 7 on classification and using, eg photographs, ICT resources, as stimulus material, establish that it is helpful to classify organisms into plants and animals and that animals can be subdivided into vertebrates and invertebrates.

• Show a selection of common living plants, eg mosses, liverworts, ferns, conifer branches, pelargonium and grass in flower. Ask pupils to suggest where, and in what environmental conditions, each might be found. Show how plants are subdivided into two groups: plants without waterproofing layers, eg mosses, which are confined to damp environments, and plants with waterproof cuticles, which inhabit a wider range of habitats.
• Ask the pupils about other features shown by the plants. Use their suggestions to form the basis of classification, eg ferns, cone-producing plants and flowering plants.

• Organise fieldwork in a suitable location, eg woodland, pond, stream, school grounds, wall, paving stones, park, sand dunes, rocky shore, and discuss with pupils the questions they will try to answer during the work, eg
• What lives there?
• Why do communities differ in different habitats?
• How can we measure sizes of populations of living things?
• Ask pupils for ideas about data they will need to collect to answer the questions, how they will go about it and what they will do with the data collected when they return to school.
• Remind pupils of how to use dataloggers to collect remote data when outside, eg temperature variations, dissolved oxygen, light intensity and humidity, and how to produce graphs from the data collected. Discuss the formats to be used for presenting results in the fieldwork activity.

• Ask pupils to suggest how they might go about finding out the size of a population of a plant or animal living in a habitat. Help them to realise the limitations of simply counting in some situations, eg where the animals are difficult to find, or where they occur in large numbers. Explain the principles behind sampling as a means of collecting this type of data in biological studies. Describe different methods of sampling populations including the use of quadrats.
• Provide groups with trays of sand, in which small steel tacks have been buried. Show them how to use small wire square quadrats to sample areas of the tray, using a magnet to remove the tacks within a quadrat. Ask them to estimate how many tacks are hidden, by taking ten quadrat samples, and to explain why taking ten samples gives more reliable data than taking one.

• Agree with pupils what data they are going to collect and show them ways of finding and observing living things in the habitat being studied. Make sure they understand issues relating to safe working and care for living organisms.
• Show pupils ways of collecting specimens of animals, eg using pooters.
• Provide pupils with resources, including keys, field guides to help them find, collect, and identify typical animals and plants that they may come across. If possible, help pupils to use a digital camera to make a record of the habitat and organisms found.

• If possible, ask different groups of pupils to make and collect data about the communities in two different habitats within the same locality, and share findings as a report in the classroom.
• Ask pupils to produce a report of their findings, describing what they did, comparing the communities and saying what led to their conclusions.

• Agree with pupils what data they are going to collect about the environmental factors of the habitat, eg temperature variations, light intensity, dissolved oxygen. Provide them with the appropriate apparatus, including dataloggers. Ask pupils to make a record of environmental conditions.

• Ask pupils to write a report, including graphs of the data, about ways in which the two environments are different and encourage them to make associations between some of these conditions, eg in ponds, warm conditions and abundant plant growth can result in low oxygen levels, fast-flowing water in streams leads to cooler conditions.

• Ask pupils to make suggestions about how the conditions in each habitat influence the communities of organisms living there, eg by asking why there is more of this here than over there, and ways in which animals and plants are adapted for the problems of living within those environmental conditions, eg pond communities contain rooted plants on the fringe and floating plants in the middle of the pond, and an abundance of free-swimming animals, while fast-running streams may have plants with long, flexible stems, and animals adapted to holding on to a stony substrate.
• Help pupils to present their work as a wall display, including images of animals and plants showing relevant adaptations.

• Remind pupils about quadrat sampling and help them to collect quantitative data about number and distribution of organisms, eg count and find out about distribution of weeds on a school field, limpets on a rocky shore or earthworms in the soil; estimate percentage cover of different plant types in different habitats or in different areas of a habitat, such as along a transect. Arrange for pupils to collect comparative information from two habitats, or different parts of a habitat for which environmental data has also been collected.

• Ask pupils to represent the data graphically, to make comparisons of the data and to suggest reasons for the distribution of organisms. Encourage them to consider the range of resources needed by animals, eg nesting sites, mates, and how environmental differences affect numbers and distribution of organisms. They should also be able to suggest ways in which organisms may influence each other, eg a large tree shading the area below it, preventing other plants from growing; availability of food influencing animal distribution.
• Help pupils to bring together all the work resulting from their field trip as a classroom display.

• Review pupils' understanding about feeding relationships by providing them with examples of food webs to analyse. Ensure that they can identify the food chains within a food web, and that they understand the terms 'producer' and 'consumer' and the flow of materials through the food chain.
• Challenge pupils to predict the effects of making changes to the numbers of one type of organism. Encourage pupils to go beyond simple relationships by considering knock-on effects of a single change, eg as the number of rabbits decreases, more grass will grow, providing more food for other grass-eating animals, whose numbers may increase as a result.
• Ask pupils to consider a range of examples of such changes in communities and their consequences. Extend the work by asking pupils to use a computer program to model changes, eg the effect of changing initial population sizes of predators and prey. Ask pupils to look for patterns in graphs produced from the data, to use these to make predictions about what will happen next and to test their predictions by allowing the simulation to run on.
• Challenge pupils to explain how plants benefit from the other organisms in the community.

• Provide pupils with data on the numbers of animals and plants in a community and what they feed on. Ask them to count up numbers of producers, herbivores and carnivores, and to look for patterns in the results and to repeat for a different set of data. Ask pupils whether the pattern in the two sets of data is the same. Show them how to represent the data as a pyramid of numbers and explain the usefulness of this model in considering the interdependence of living things.
• Show pupils examples of inverted pyramids of numbers, eg involving an oak tree, and ask them to explain how these are different.

• Present pupils with a case study, eg plans to cut down a number of trees in a school's grounds. Provide relevant information, such as food webs for the community, population sizes, etc. Ask pupils to report how this action might affect the living things in the area including ideas they might have about protecting their local environment.