Science at key stage 3    (Year 7)

• Ask pupils about environments or habitats they studied at key stage 2 and explain that in the first part of the work in this unit they are going to look at features of habitats.
• Provide pupils with stimulus material, eg video of the Arctic, poster of woodland life, picture of cacti in a desert, underwater scene, worms in a wormery. Ask the pupils to describe the physical features of each habitat and identify major environmental factors, eg light intensity, oxygen availability, temperature range.
• With pupils, decide on a limited list of animal and plant species for each habitat. Remind pupils of the importance of making sure listeners can follow their argument, and ask them, in groups, to use secondary sources to investigate how species are adapted to life in one habitat and to present their findings, eg orally, using overhead transparencies (OHTs) or flip charts.

• Ask pupils to predict how physical environmental factors around the school, eg light intensity, temperature, humidity, noise levels, would change over a 24-hour period and how they could measure the changes. With pupils, set up instruments, eg datalogging equipment with a light probe, automatic weather station, temperature and sound sensors, to monitor changes. Provide pupils with data about environmental changes around the school over a 24-hour period and help them to describe what these show and to identify links between the different changes.
• Ask pupils to suggest how the population of plants and animals in the school habitat would change over the same time, eg crows and starlings visiting dustbins in daylight, squirrels visiting after school finishes, foxes after dark; slugs, cats, mice, bats active at night. Using their ideas, secondary sources and first-hand observation where possible, help pupils to generate comparative lists of animals active during the day, at dawn and dusk and those which are nocturnal.

• Using observations of small invertebrates in the school grounds or elsewhere, ask pupils to generate a suitable question about how the activity of an invertebrate, eg woodlice, snails, brine shrimps, daphnia, varies with environmental changes, eg dampness, light/dark, and to plan and carry out an investigation.
• Help pupils to produce an account of what they did, focusing on the size of sample they used, the factors they could and could not control and how confident they were in their results.

• Provide pupils with overwintering structures or photographs or video clips of these as stimulus material, eg onion bulb, pupa, twig with buds, carrot, plastic bag of hair from a moulting pet. Ask pupils to suggest when they would normally be found and their function. Show videos of habitats at different times of the year and ask pupils to identify differences and describe the consequences of these for the organisms in the habitat. Ask pupils to describe from their own knowledge how plants in the school habitat change over the year and predict the likely effects of the changes on the animals in the locality.
• Provide pupils with key words and phrases, eg migration, hibernation, overwintering of pupae, dormant structures, making food stores, thicker insulation, and ask pupils to use secondary sources to find out about these and how they help animals avoid climatic stress. Ask pupils to describe what they found out and help them to contribute to a summary sheet about seasonal changes.

• Provide pupils with a list of adaptive animal and plant characteristics and ask them to decide on the six most important for a particular habitat. Ask them to explain their choices and ask others to evaluate these critically, identifying the advantages the adaptation gives the organism. Help pupils to use the results of the work to make generalisations about adaptation.

• Review pupils' knowledge of predators and prey by providing stimulus material, eg posters, photos, pictures, video clips, preserved and live specimens, of predatory animals and prey species, eg eagle, dog, pike, bat, spider, rabbit, antelope, snail, and asking pupils to describe how the predators are adapted for finding, catching and killing their prey and how prey species are adapted for detecting and avoiding predators. Help pupils construct tables of general features of predators and prey, eg predators may have eyes forward, acute vision and sense of smell, sharp claws/talons/beaks for piercing and tearing, may ambush or hunt by stealth, whereas prey may have eyes at the side, acute hearing and sense of smell, be easily startled, be nocturnal, camouflaged.
• Ask pupils to investigate the effect of beak shape in seed-eating birds, eg by using blunt and fine-pointed forceps to pick up and transfer seeds of varying sizes from a dish in one minute. Discuss with pupils how much data they need to gather for reliable conclusions.

• Establish by quick questions pupils' understanding from work in key stage 2 of terms related to food chains, eg producer, consumer.
• Present pupils with stimulus material, eg a habitat poster such as meadowland or woodland, and challenge them to make as many food chains as they can. Ask them to identify producers, consumers, herbivores and carnivores. Explain the direction of the arrows in the food chain and relate to energy transfer, with the Sun as the ultimate source of energy. Ask pupils to write a sentence about each food chain, using links of cause, eg so, because, since.
• Ask pupils to find examples of animals that occur in more than one food chain and to explain what this shows about their food sources. Show pupils a food web and explain that it is a more accurate representation of feeding relationships.
• Help pupils use the food chains they have generated to construct a food web for display. Provide pupils with secondary data so they can practise identifying food chains within a food web and constructing food webs from food chains.
• Establish with pupils that food webs, food chains and terms, eg predator and prey are ways of describing feeding relationships.

• Ask pupils to suggest likely places to find plants and animals in the locality of the school, what species they think they might find and how the plants and animals might be linked in food webs. Encourage pupils to consider what evidence we use to find out what animals eat, eg owl pellets, remains near lairs and nests, thrush anvils, observations, teeth marks, bird droppings showing coloured berries have been eaten.
• Show pupils how to use simple equipment and techniques, eg direct observation, pooters, tree beating, and ask them to find, identify and record as many species of plants and animals as possible within the school locality.
• Ask pupils to record any observations which help to identify a food source, eg a greenfly found on a rose bush, woodlice found under decaying wood, fly entangled in a spider's web, and to note plant features which may deter animals from feeding on them, eg prickles on holly, thistles, sting on nettles. If appropriate, extend this work using secondary sources.
• Help the pupils to use the information gathered to construct a database using a data-handling programme.

• Provide pupils with secondary sources, eg reference books, CD-ROMs, databases, to find information about the diet of animals identified in the previous activity, and remind them how to use the index, contents section, key words and hotlinks. Ask them to add the information to the database. Ask them to use the information to construct food chains using the species identified, and to describe what the food chains show. Help the pupils to link their food chains together into a food web. Challenge the pupils to explain any missing links, eg absence of carnivores, such as owls or hawks. Help pupils to produce a display of their food web(s).

• Challenge pupils to suggest where there is competition between species in the food web. Reinforce their ideas by removing a plant species or adding two or more consumers and ask the pupils to predict the consequences.
• Extend the work by asking pupils to use food webs, eg those generated in previous activities, to practise predicting the effects of altering the numbers of various organisms in a web. Use ICT simulations to test out the predictions made.

• Construct a paper and wool model of a food web identified in the previous activity. Remove one animal species from the web, eg by cutting the strands of wool holding it in place. Ask the pupils what will happen to the animals that feed on that species. Challenge pupils to identify any other effects on the food web.
• Extend by providing pupils with a food web in which at least one animal is a seasonal visitor and asking them to identify differences in the food web in other seasons.