The move forms part of the Government's relaxation of lockdown rules aimed at getting more children back to school.
Under the new measures, all pupils in nursery, reception, Year 1 and Year 6 were allowed to go back to school from Monday.
Some Staffordshire schools have already been looking after children of key workers amid the pandemic.
Councillor Philip White, cabinet member for learning and employability at Staffordshire County Council, said: "Opening schools has to be a balancing act between ensuring pupils are not disadvantaged in their studies and keeping the virus contained.
"This is why schools across Staffordshire have been working hard to determine how they can open to more pupils whilst maintaining social distancing.
"Arrangements will differ from school to school but each school will have already informed parents of the measures they are putting in place.
"With the new Test and Trace system launched last week, there are now more measures in place to quickly deal with any issues if they occur.
"Schools haven’t been closed through this pandemic – many have been open to the children of key workers, and many more have been helping pupils continue their studies online.
"Most of our schools will be opening to certain year groups today, while others will open in the coming days as soon as they are confident they have the right measures in place to protect pupils and staff.
"We will continue to support all schools, and give them the advice and guidance needed to operate safely."