The following information and guidance is provided by QCA at  http://www.nc.uk.net/gt/science/teaching.htm

It is vital to enrich and extend the curriculum for pupils who are gifted in science by using a variety of methods, depending on the context. For example:
	sharing and encouraging pupils' curiosity, allowing them to speculate without necessarily needing the correct answer
	applying a higher level of skill to a common question or problem to be solved by the whole class
	enriching and extending their breadth of knowledge by drawing on information that goes beyond that provided for most pupils, including going beyond the national curriculum
	accelerating pupils through a particular stage in the national curriculum
	giving pupils access to more demanding texts or ICT -based information for research
	occasionally giving pupils the chance to modify an investigation to make it more challenging
	challenging pupils to provide explanations and connections, as well as information
	encouraging them to take part in activities outside the school and allowing them to take some responsibility for organising such activities
	encouraging pupils to go to local science lectures or similar events
	encouraging them to carry out further investigative work at home, if necessary by providing simple equipment and materials (with due regard to safety).

Enriching and extending the curriculum can be a way of avoiding accelerating pupils into the next year in order to maintain the challenge.