Image copyright Getty Images Image caption There are concerns pupils' learning will overly rely on the knowledge and experience of individual teachers

Pupils' learning could be "left to chance" because of a lack of clarity in Wales' new curriculum, education bosses have warned.

They told assembly members too much of the draft curriculum so far was "generic, poorly defined and weak on knowledge and skills development".

A draft will be published in April and it is due to be rolled out from 2022.

The education minister said she was concerned there was a misunderstanding of the vision behind the curriculum.

The Welsh Local Government Association (WLGA) and the Association of Directors of Education in Wales (ADEW) raised their concerns in joint evidence to the Assembly's children, young people and education committee, which is reviewing how the reforms are progressing.

'Grandiose themes'

"It is likely that pupils' knowledge, understanding and skills development will be left to chance, i.e. relying heavily on the knowledge and experience of individual teachers as opposed to an entitlement defined by the curriculum," they said.

They said pupils without "strong family support" were at risk of missing out the most.

In the area of language and literacy learning, they said: "There are many high-level and grandiose themes at the expense of the nuts and bolts of language development - speaking, reading and writing."

Science and technology appeared to be "the least developed" area.

Although there had been some improvement, there remained poor communication with schools on the progress of reform, they added.

Image copyright Thinkstock Image caption Prof Graham Donaldson's independent review set out a shake-up of the curriculum in Wales

The new curriculum will be introduced in primary schools and the first year of secondary in 2022 - those pupils will all learn under the new curriculum as they move up the school years.

Any child currently in Year Three or below will be taught under the reformed system.

Schools and officials have been developing content for the draft curriculum.

Reality of reform

"The landscape is awash with experts getting 'excited' about curriculum reform," the WLGA and ADEW wrote.

"The reality is that workload-weary teachers will have to try to make it work on the ground."

They raised concerns that the number of reforms in schools potentially distracted from the actual teaching of children.

They also said:

Maths was the best-defined area of the curriculum so far.

It was a concern that "modern foreign languages, such as French, are not explicitly identified... they are referred to as 'other languages'. The lack of prominence is likely to undermine their importance in the curriculum".

A lot of topics had been included in "humanities" but there was a "lack of sufficient detail".

Physical and sporting development was not mapped out well and there was no mention of the word "sport".

There was a "lack of clarity" around the expressive arts.

Image caption Education Minister Kirsty Williams told the children's committee progress was on track

On Thursday, Education Minister Kirsty Williams appeared in front of the education committee and said progress on the new curriculum was "in a really good place".

The minister said the evidence from the WLGA and ADEW was "disappointing" and appeared to be based on out-of-date information.

She also said they had not raised concerns when there had been previous opportunities to do so.

She added: "I am concerned [what is being suggested] is in danger of taking us to a situation where we have long, detailed lists of content which is very much against the vision of what we're trying to achieve."

"Now clearly that is a matter of concern to me that there may be a misunderstanding of [that] vision."

Plaid Cymru committee member Sian Gwenllian said the Minister should "urgently consider" the "scathing criticism" and called for her to "come up with a plan to address this major problem about the lack of substance in the contents of the curriculum".