Well these will kick off again in May 2008 for all UK schools.
I always recommend practicing the past papers to get the best results. This means going through them, and spending time looking at the questions you find most difficult.
The Key Stage 2 and Key Stage 3 are statutory tests before you get to GCSE. These are taken in Year 6 and Year 9 (although more and more schools are taking these in year 8, to give a longer GCSE course - and more change of higher GCSE grades!).
At KS2, pupils sit English, Maths and Science - three papers in English, two papers in Science, and two written papers and one oral paper in Mathematics.
At KS3, pupils sit the level 4-7 papers in English, and then sit either the 3-5, 4-6, 5-7, or 6-8 papers in Mathematics - they are put in for the appropriate level by their school according to their academic ability. There are only two different levels in Science - the 3-6 and the 5-7 levels. Once again the school will judge which paper each pupil is aligned to, and they will sit the exam accordingly. The more difficult papers are the higher tiered papers, with 6-8 being the most difficult in Mathematics and 5-7 in Science.
http://www.actual-sats.co.uk/ is the publisher for the Key Stage 2 and Key Stage 3 papers, and they provide three packs. The KS2 pack comes with all the papers and all the levels, and the mark schemes and on-line mental maths are also available. They do two packs at KS3, a higher tier, which contains the 5-7 & 6-8 maths papers, 5-7 science papers and 4-7 english papers. The lower tier contains the 3-5 & 4-6 maths papers, 3-6 science papers and 4-7 english papers.
These packs can also be obtained from http://www.sats-past-papers.co.uk/ where you can also get past papers from 2004, 2005, and 2006, as well as the latest 2007 papers.
After KS3, pupils are usually streamed according to ability in mathematics and science - those that attain good KS3 levels will be in the higher sets in maths and science. At GCSE, there is a combined science course, as well as the traditional physcis, biology, and chemistry split sciences. The split science are usually only offered to the more academic students, and so KS3 results in science becomes hugely important for what comes later for children at GCSE, and ultimately their overall GCSE results.
