NAPLAN preliminary results released yesterday dealt a blow to the state with years 3, 5, 7 and 9 students rating second worst in the nation in 11 of the 20 categories.

The only area in which the state met the national minimum standard was in year 7 reading, but its overall ranking has dropped from fourth last year, to sixth.

Students in years 3, 5 and 9 lagged in spelling, with 14 per cent of year 9s falling below the national benchmark.

Education Minister Jeremy Rockliff said it was troubling to see fewer Tasmanian students had reached minimum spelling standards than last year.

He said the recently introduced specialist literacy and numeracy teachers were needed to improve educational outcomes.

"There can be no sugar-coating the fact that Tasmania continues to be ranked sixth or seventh out of all states and territories on most indicators," he said.

"While there was some improvement compared to the Australian average, there is still much work to be done."

University of Tasmania curriculum theory professor Bruce Waldrip said the years 3, 5 and 7 percentage results were really not that far behind the rest of Australia.

He said year 3 results were showing slight improvements.

"Where I want to see the biggest change is in the early years because those changes flow down in the later years," Professor Waldrip said.

He said specialist teachers could increase results, but would not have a long-term impact.

"The work that we have done on reasoned thinking [in classrooms] gives us greater gains than when you have a specialist [where] there is not that connection with the rest of student learning," he said.