Not enough secondary schools are embracing good practice from feeder primaries to help raise academic standards among new Year 7 pupils, it will be claimed today.
Jane Davidson, minister for education, lifelong learning and skills, is expected to say "too few" new transition plans aimed at building on pupil achievement at primary level are up to scratch.
Not enough schools are liaising to ensure continuity of assessment criteria and joint curriculum planning, she will tell delegates at a conference in south Wales.
And, while secondary teachers are observing teaching techniques and future pupils in primary settings, pupils are still expected to cope with a complex curriculum on entry to secondary school.
The dip in pupil achievement when youngsters move to secondary is well-documented. For example, research by Cambridge university and the National Foundation for Educational Research found 40 per cent of pupils lost motivation and made no progress after transferring to secondary.
So from September 2007, all Welsh secondary schools with an on-going relationship with one or more feeder primaries will be legally required to have a transition plan in place.
But unions say time-starved teachers need more resources to allow them the "luxury of getting out of the classroom and into primary schools".
Speaking at today's "strengthening the links" conference, organised by the Welsh Secondary Schools Association and the Wales Primary School Association, Ms Davidson will praise schools for coming up with some great plans to make a child's move to Y7 happy and stress-free.
But she will also be critical of parallel plans to raise educational standards. In her draft speech, Ms Davidson says: "Too few schools have made quite big changes to how they organise teaching in Y7 to help pupils adjust to the more complex secondary school curriculum. In these schools, the form tutor teaches at least one subject, tutor periods, and personal and social education."
Assessment, continuity in learning and advice on drawing up transition plans are all tackled at the conference, at the ESIS centre in Trefforest, Pontypridd.
But Geraint Davies, Welsh secretary of teachers' union the NASUWT Cymru, said: "The extra workload involved in drawing up these plans must be alleviated with extra resources."
The Assembly government has ring-fenced pound;9.5 million through LEA budgets for activities and staff development linked to school transition plans.
Money is also available via grants for KS2-KS3 transition, with another Pounds 5m over three years for local authorities working with schools on projects.
Mick Fahy, head of Ebbw Vale comprehensive, Blaenau Gwent, said it had used cash from the LEA to buy interactive whiteboards and invested in extra training in primary techniques.
He said: "There has been a lack of real awareness and understanding in secondary schools of how pupils learn in primary. There are major changes to teaching and learning styles."