For the first time, the NAPLAN assessment is taking place in March instead of May to help teaching and learning programs for the rest of the year.

But the organisation running the test - the Australian Curriculum, Assessment and Reporting Authority - is reminding parents, teachers and students to keep it in perspective.

ACARA chief David de Carvalho said while NAPLAN was invaluable as a national assessment tool, it was unnecessary for schools to feel pressured or students to be apprehensive about the test.

"It's one test held every two years. It doesn't measure overall school quality. It's not meant to tell us everything about a student or their achievement," he said.

Instead, results are used to show governments, education authorities and schools whether Australian children are reaching important literacy and numeracy goals.

It also helps parents and carers see how their child is progressing against national literacy and numeracy standards.

Mr de Carvalho thanked teachers across the country for their efforts to bring the test into the first term of the school year.

He said the move aimed to give teachers earlier insights about their students and consider what support will be needed in the year ahead.

The testing window starts on Wednesday and will assess 1.3 million students from years 3, 5, 7, and 9 at 9800 campuses across the nation.

Australian Associated Press