Science at key stage 3    (Year 7)

• Provide pupils with stimulus material, eg pictures, video clips, to review their knowledge of reproduction in animals. Ask pupils to find out about the reproduction and development of certain animals, eg fish, frogs, including information on fertilisation using texts, CD-ROMs and to make notes or summaries of their ideas.
• Discuss how eggs are fertilised externally in some animals, eg fish, frogs, using video clips as illustrations and pointing out the numbers of eggs fertilised at one time. Ask pupils to suggest why this is.

• Remind pupils of the differences in the number of eggs produced by animals where fertilisation is external and those where it is internal. Provide pupils with stimulus material and secondary sources and ask them to identify patterns in the number of eggs, internal and external fertilisation or development, aftercare, growth pattern and chance of offspring surviving to maturity in the species used.
• Discuss the advantages of retaining the young in the body and feeding the young on milk after birth, eg continuous access to nutrients, protection from predators. Show pupils video clips of other mammals' offspring immediately after birth and ask them about their experience of newly born pets. Establish that newborn humans are more dependent than some other species. Help pupils to agree some broad generalisations from the data considered.

• Using models, video clips or other illustrations, help pupils to identify, name and describe the functions of the mature human reproductive organs. Ask pupils to annotate diagrams of male and female reproductive organs.
• Remind pupils of work on cells and establish that for fertilisation to occur, a male cell (sperm) fuses with a female cell (egg). Establish that sperm are produced in testes and eggs in ovaries. Talk with pupils about sperm being deposited in the vagina and having to move to where the eggs are and eggs being moved down the oviduct, illustrating, eg with video and software simulations. Explain fertilisation in terms of the fusion of nuclei of sperm and egg.
• Discuss with pupils, illustrating with, eg video clips, photographs, software simulations, how the cells divide and increase in number. Ask pupils to draw, or label, and sequence pictures or diagrams illustrating ovulation, fertilisation, cell division and implantation.

• Show photographs or video clips of sperm and egg cells. Ask pupils to compare them and suggest how they are specially adapted for their functions. Ask pupils to draw and describe or annotate drawings of egg and sperm cells, identifying their main features.

• Use quick questions to check pupils' recall of cell structure and making new cells. Review fertilisation in terms of the fusion of nuclei and discuss how this results in characteristics being passed from parents to offspring.
• Ask the pupils to speculate on how identical and non-identical twins occur, eg by providing them with statements containing correct and incorrect explanations from which to select.
• Establish with pupils that, whether fertilisation is internal or external, it involves the fusing of male and female nuclei and involves the combination of characteristics of both parents.

• Remind pupils of the differences between external and internal fertilisation. Ask them about the numbers of eggs and sperm in each case and to suggest reasons for any differences. Find out what pupils know about human egg cells, eg where they are produced, how often they are produced, and how a woman might know if she is pregnant or not. Using pupils' suggestions and video or CD-ROM simulation introduce the stages of the monthly cycle.
• Help the pupils to construct a diagram of the days in the cycle, marking when menstruation and ovulation might occur and when the uterus lining is thickening. Discuss with pupils the variation in cycle length and practise calculating when a woman might ovulate and when her period is due. Explain that the menstrual cycle also prepares the uterus for a fertilised egg and identify the time in the cycle when fertilisation is most likely.
• Establish that, on the whole, humans have one offspring at a time and that the human reproductive system is designed to try to make sure that the one offspring survives.

• Use quick questions to establish pupils' knowledge of pregnancy. Use photographs, models, diagrams, video clips, CD-ROMs or ultrasound scans to look at the changes in a developing foetus from implantation to birth and discuss the sequence with pupils.
• Identify the structures within the pregnant uterus and explain the functions of the amnion and amniotic fluid. Discuss with pupils the foetus' need for nutrients and explain the role of the placenta in materials exchange. Ask pupils to label a diagram and use arrows to show movement of oxygen and nutrients from the mother to the foetus and the movement of carbon dioxide and other waste products from the foetus to the mother.

• Challenge pupils to explain why, at one time, teenage girls were offered the rubella vaccine, but boys were not. Using secondary sources, discuss with pupils the passage of alcohol, substances from cigarette smoke and drugs across the placenta. Ask pupils to make a poster or leaflet to explain, eg why vaccination against rubella is important, how smoking can affect a developing foetus.

• Discuss with pupils the processes of birth, using video, photographs and diagrams as illustrations.
• Ask pupils how newborn babies obtain the nourishment they need. Describe the composition of breast milk. Review with pupils their knowledge of the care needed by babies.
• Use video clips to show that a baby is responsive to its world, eg has reflex actions when born, such as head turning when its cheek is touched.

• Ask pupils to produce a short illustrated account of the growth of a foetus and birth, which could be used with a younger sibling when a new baby is about to arrive in the family. Ask them for their ideas of the main points to include and how to organise the material.

• Use quick oral questions to elicit pupils' knowledge of the human life cycle, eg babyhood, childhood, adolescence, puberty and adulthood.
• Ask pupils to recall times when they grew rapidly in primary school and identify the main ways in which they changed. Use secondary data of height at different ages to plot growth charts and identify the main periods of time when rapid growth takes place.

• Remind pupils of their work on cell division. Discuss growth and how pupils should measure it, eg weight gain, height changes, girth. Pupils explore the range of heights in the class and present their data. Help pupils to think about how many individuals are needed for measurement to ensure reliable information, what other factors should be considered, eg boys/girls, and how they will present their data.
• Discuss with the pupils trends in the data. Show charts and graphs to illustrate the range of expected heights and weights at this age. Help pupils compare the ranges shown by the charts with the data collected by the class and discuss reasons for similarities and differences in terms of sample size.

• Discuss how external adult features change during puberty, eg breasts, wider hips, facial and body hair, voice changes, stronger body smell. Explain that circulating hormones cause the development of secondary sexual characteristics and reproductive organs.
• Challenge the pupils to provide evidence about whether emotional maturation during adolescence proceeds at the same rate as physical maturation in puberty, eg by selecting or modifying personal problems from a teenage magazine or by creating stories about secondary sexual characteristics or emotional maturation. Ask pupils to discuss scenarios in groups and then produce and present a reply to the rest of the class.

• Provide pupils with a series of statements about the human life cycle, the processes of fertilisation, embryo development and birth, and about the specialisation of cells. Ask pupils to sort the statements into groups and use them to make summaries of the ideas encountered in the unit.