Science teachers have expressed concern that the slimmed-down curriculum omits crucial details. The current, 18-page programme of study has now been cut to less than five.
On electricity and magnetism, for example, six detailed points ensure topics such as how to measure current and voltage are covered. But under the revised curriculum, it has been reduced to nine words: "Electricity in circuits can produce a variety of effects."
No fewer than 32 points of "life processes and living things" are compressed into five on "organisms, behaviour and health".
Science bodies said that teachers have A-level and GCSE syllabuses to guide them at key stages 4 and 5, and without more guidance at key stage 3, teachers would end up using national tests for the same purpose.
"The danger is that teachers will have to teach completely to the test and nothing will change," said Colin Osborne, Royal Society of Chemistry education manager. "We are perfectly happy with the science that is covered, but without more guidance teachers will have to keep re-inventing the wheel."
There was also concern that the reforms, which coincide with the introduction of new science GCSEs next year and new A-levels in 2008, could overwhelm teachers.
Colin Osborne said: "Three revisions in two years is not a good thing."
Daniel Sandford-Smith, Institute of Physics education manager, agreed: "We are very concerned about the timescale for the implementation of this and the workload it is going to entail for science teachers.
"If this is about giving teachers more flexibility to innovate, then they need time to develop that."