The changes follow strong criticisms by an expert working group from the Royal Society of Edinburgh and feedback from teachers.
The Scottish Government acknowledged that the science experiences and outcomes - the first set to be drafted - contained "a strong concentration on the development of opportunities for new approaches to learning and teaching, with insufficient reinforcement of conceptual development in science".
The revised science guidance is scheduled for release in mid-April. A Government spokeswoman added that exemplification would follow in due course.
Teacher feedback, distilled in a research study commissioned by Learning and Teaching Scotland, and the RSE report highlighted the need for exemplification of how the outcomes could be translated into learning in the classroom.
The development of A Curriculum for Excellence and its role in preparing pupils for higher education and science-based careers formed part of the programme this week at the annual Science at the Parliament event.
Meanwhile, an HMIE report published this week has warned that schools are falling far short of expectations in adapting science teaching to ACfE, particularly in cross-curricular working and active learning.
Senior chief inspector Graham Donaldson observed that, although there were "many strengths" in science education, there were also "continuing areas of weakness".
Inspectors found some good links between science and different parts of the curriculum, but "in most schools, this was poorly developed".
The combination of weaknesses in cross-curricular working and a lack of reliable assessment information in primaries made children likely to regress in science when they entered S1. In secondary schools, teachers were good at consolidating knowledge but did not always use it effectively to encourage thinking and understanding, according to pupils' opinions collated in the report.
"The teacher talks too much - we just have to listen and copy down notes all the time," one said.
Even though teachers at all stages were making more use of ICT, "learners' use of ICT to collect, analyse and present scientific data was often limited".
The report recommends a bigger role for co-operative learning, where children work together, "rather than just alongside each other".
Frequent good examples of practice were also highlighted.
Teachers in one secondary science department had spotted that many young people in S1-2 had weaknesses in literacy skills, which limited their progress in science. They worked on a cross-curricular solution with English teachers, so that pupils learned the importance of using scientific terminology accurately and providing evidence to support arguments.
Rhona Goss, vice-chair of the Association for Science Education Scotland, said it was too early to judge schools against the new curriculum, which is not to be fully implemented until 2010. The science outcomes for ACfE had not been finalised, and most schools were still "unpicking" them, she said. Changes would be more about "evolution rather than revolution", with ideas such as active learning, co-operative learning and formative assessment taking time to bed in.
Jack Jackson, former national specialist for science in HMIE, said it was to be expected that there would be significant gaps between schools' daily practice and the new curriculum. Science teachers were not as used to encouraging open debate in classes, for example, as colleagues in other departments, he said. Nonetheless, moral, social and ethical issues were being discussed in secondary and upper-primary science classes more than was once the case.