with documents setting out its approach to blended learning and the findings of the preparatory research it conducted in the US.
These reveal that Ark sees blended learning as "an opportunity for revised teacher roles". The chain notes that other schools using the system have introduced roles that include "master teachers" responsible for "leading full-class or small group instruction".
There have also been "teachers responsible for leading small group instruction and guiding self-paced work" and "teaching assistants who are responsible for helping out with tutoring.and supervision of online learning".
One document reveals that Ark looked at Rocketship as a major part of its research. The not-for-profit charter school chain has pioneered the model in the US and now operates nine schools in Milwaukee and San Jose, teaching 5,000 pupils who spend a quarter of their school day online.
Interviewed on British radio earlier this year, Rocketship chief executive Preston Smith said that computers had allowed his organisation to "really rethink the school day". He was initially evasive about what that meant for staff numbers but eventually admitted: "We have fewer teachers than a traditional school serving the same number of students."
He said that online sessions at Rocketship were facilitated by "noncredentialed staff", while qualified teachers were used to teach higher-order and critical thinking skills.
"We are paying around 30 to 50 per cent more than the surrounding districts, per teacher," Mr Smith added. "If your kids are performing incredibly well, and you have eliminated the achievement gap in your classroom, and your kids are on a par with the most affluent kids in the country, we should be paying you incredibly well because you are doing amazing work. We want to help you realise six figures, if not more, as quickly as possible."
Rocketship's approach initially led to impressive test results, but these have declined as the chain has expanded, leading the charity to rethink its approach to blended learning.
Christine Blower, general secretary of the NUT, said: "The use of the word `efficiencies' is all very nice but what it really means is cuts. If we have got circumstances where we have got children ostensibly being taught, but actually sitting in front of computers for a significant amount of time and not having routine access to a teacher for every lesson, then that would be a completely wrong departure.
"We would be concerned about the loss of teaching jobs and about the loss of proper good quality education for all children and young people."
Dr Gwyneth Hughes, from the University of London's Institute of Education, has researched the use of blended learning in higher education and found that its success depended on how the system was designed.
"The common pitfalls tend to be either creating too much student dependency on the online moderator, or the other extreme when the tutor is virtually absent and the students are left to their own devices," she said. "But some students have been quite surprised by the depth of engagement they can have with their peers online, because they expected it to be quite poor compared with face-to-face."
An ARK spokesperson said: "Our plans are at a very early stage, but it is worth reflecting that our blended learning pilot at King Solomon Academy did not mean fewer teachers or bigger classes, but ensuring that pupils have access to the latest in educational technology and techniques."
What's in the mix?
Blended learning is usually seen as a technology-based mix of computer learning and teacher-delivered lessons. It has already made inroads into higher education, with some suggesting that big university lectures could become a thing of the past.
Blended learning is designed to be more engaging than traditional teaching, allowing students to work at their own pace and be more involved in their assessment. It is also meant to make teaching more efficient.
At school level the approach is still being worked out. US pioneer Rocketship Education began with a "lab rotation" or "station rotation" model, with online learning in separate computer or learning labs.
But after concerns were raised that this was too factory-like, Rocketship introduced a "classroom rotation" model. This allows small groups of pupils to rotate between online learning, project work and direct instruction within the same room.
This approach has been trialled at one of Ark's existing schools, King Solomon Academy in London.