The move to a more flexible school curriculum in England is being rushed, leading science organisations claim.
Curriculum changes are aimed at greater "personalised" learning
Learned societies, teachers and others say it is alarming that changes for 11 to 14-year-olds are not being piloted.
Schools are under too much pressure from other developments to implement the changes in 2008 successfully, the group argues. They should be postponed.
The government said that, far from being rushed in, the changes were the result of extensive consultation.
Its aim is to give teachers more scope to help children master the basics and greater flexibility to enliven lessons and personalise learning.
The warning has come in a report from the Science Community Partnership Supporting Education (Score), made up of the Association for Science Education, Biosciences Federation, Institute of Biology, Institute of Physics, Royal Society, Royal Society of Chemistry and the Science Council.
It has been produced to coincide with a debate on the subject in the House of Lords on Thursday.
It is written as a response to the Lords science and technology committee's report on science teaching in schools, which said pupils in England found science A-levels too difficult and other subjects more "funky".
Score says the authorities need to take notice of the public consultation on changes to Key Stage 3 which is underway.
The Department for Education and Skills and the Qualifications and Curriculum Authority "will need a strong justification for ignoring responses that suggest the development process is too short for successful implementation".
It believed there would be considerable advantages in allowing schools to pilot the changes from 2008 but not insisting they all change until assessment material was available in 2011.
In addition to preparing for those changes, science teachers will next year also be:
- teaching the second year of new science GCSEs
- preparing to deliver new courses for separate sciences
- preparing for new A-level courses and extended projects
- preparing to deliver science elements in the new specialised 14-19 Diplomas.
The Royal Society's education director, Professor Michael Reiss, said: "It's vital more young people are interested and enthused about studying the sciences.
"It is therefore alarming that changes at such an important time for young people - their first taste of secondary school - are being rushed along on the wave of reform without any piloting."
Daniel Sandford-Smith, of the Institute of Physics, said: "Giving teachers more flexibility to exercise their professional judgement is good.
"However, reducing the constraints of the curriculum without providing proper guidance for teachers runs the risk that some will become more reliant on the content of Key Stage 3 tests to direct their teaching.
"This kind of 'teaching to the test' actually undermines the government's ambitions in making these changes to 'personalise' pupil's learning."
Score also says publishers of educational materials are struggling to keep up, and says it is concerned about the number of errors already creeping into resources for schools.
A spokesperson for the Department for Education and Skills said the Royal Society had been directly consulted in developing the proposals.
"The changes are not being rushed in - far from it. Our work is the result of extensive consultation with industry, academics and the Royal Society themselves and have widespread support.
"Teachers are not being asked to tear up lesson plans and start again from September 2008.
"The Key Stage 3 changes will be phased in over three years and will be supported by a full package of guidance and support to teachers of science and all other teachers, starting in September."
A spokeswoman for the Qualifications and Curriculum Authority said changes to the way science was taught would enable a smoother transition into GCSE study.