New figures show that less than a third of Hwb+ accounts had been used in the autumn term.
Set up in 2012 and having cost £4.5 million to date, Hwb+, is a virtual learning environment, available to all pupils aged three to 19 in Wales as part of a drive to increase the use of technology in the classroom, provide a forum for debate and discussion, as well as share good practice.
But opposition party Plaid Cymru, which requested the figures under the Freedom of Information Act, has branded Hwb+ another good idea which is not working in practice.
Only 162,837 of the 529,481 Hwb+ sites had been accessed between September and November last year.
Plaid’s education spokesman Simon Thomas said: “The ideas behind Hwb are sound in principle. In practice, as is so often the case with the Welsh government, the delivery does not seem to happen on the ground.
“Clearly some schools are using it successfully but others need support and it needs to be as user-friendly as possible. Wales needs young people equipped with the skills that are necessary to make the future Welsh workforce a global competitor.”
According to the figures, 156 of the 218 secondary schools that have Hwb+ sites (72 per cent) have taken part in special online training. The proportion is greater in the primary sector, with 1,317 of 1,399 Hwb+ schools (94 per cent) signing up.
Hwb+ was one of several recommendations made by the Digital Classroom Teaching Task and Finish Group, which reported to ministers in March 2012.
The Welsh government said the learning platform had proved “hugely popular” among pupils and teachers with more than 98 per cent of schools having been set up with their own Hwb+ site.
A spokesman added: “The minister recently confirmed a multi-million-pound extension that will ensure the project continues until August 2018. As part of the extension, a Hwb+ Centres of Excellence Programme will now be commissioned which will accelerate the adoption of the Hwb+ learning platform across schools in Wales.”