The Federation's council voted for the strike last weekend, which they say followed 18 months of negotiations with the NSW government.

Senior vice president Amber Flohm said Tuesday's planned action would highlight the "gravity of the situation".

"All indications are that teachers in the Riverina will support, in large numbers, the 24 hour strike that the Federation directed its members to undertake," she said.

"We recognise the disruption that parents will face on this day.

"But ... every single day across the Riverina, classes are merged and classes are moved to minimal supervision.

"So while we understand that it may be inconvenient for some parents, this is about securing the future supply of teachers for the ongoing provision of public education."

The teacher's federation has released a NSW government briefing document obtained through a freedom of information request, which describes a "large and growing shortage of teachers" and a near-30 per cent decrease in enrolments in teacher education courses in the four years to 2019.

Ms Flohm said workload and wages were a key contributor.

"The only way to stop the shortages and to recruit the teachers we need is to invest in teachers through more competitive salaries and lower workloads," she said.

"The department itself, warned and I quote, 'On average, teacher pay has been falling relative to pay in other professions since the late 1980s, and this makes it a less attractive profession for high achieving students'.

"Teaching is being rightly seen as an unattractive profession, not only for our brightest young people entering into teaching, but for those who are leaving in droves because of that workload."

Sydney University and Curtin University found teachers they surveyed spent an average of 43 hours per week in school and a further 11 hours per week at home.

An additional two hours for planning being timetabled for teachers and a wage rise of at least five per cent as recommended the Gallop inquiry are among asks of the government.

"There have been no decreases in the face-to-face teaching loads of secondary teachers since the 1950s, and primary teachers since the 1980s ... and you look at the complexity of today's classrooms," Ms Flohm said.

"The government knows what the problem is. The question is now will they listen?"

The NSW Department of Education said it would update schools and parents while urging the Federation to comply with the Industrial Relations Commission's order to stop strike action.

The current Teachers' Award expires on 31 December 2021 and a new agreement has not been reached; the matter will be arbitrated by a Full Bench of the Commission, scheduled for May 2022.

"Rather than wait until the outcome of the arbitration in May, the department has made an application for an interim Award to deliver a 2.5 per cent salary increase ... this is the maximum amount allowed per annum under the Industrial Relations Act," the Department said.

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"We are doing all we can to ensure teaching and learning continues without disruption."

Tuesday's action follows Teachers Federation members walking off the job this year at Howlong Public School, Finley High School and schools in Deniliquin.