The Blackburn-based company and private equity firm Apax Partners – which owns a 25 percent stake in Promethean – sold a combined 92.9m shares at 200 pence.
The shares represent 46.4 per cent of Promethean's enlarged share capital.
Promethean was valued at £400m.
Goldman Sachs and J.P. Morgan Cazenove were the bookrunners.
Promethean will use the IPO proceeds to repay shareholders' loans and be in a modest net cash position after the flotation.
Chief executive Jean-Yves Charlier said: "The IPO is a natural move for the company and has been oversubscribed 3.3 times.
"Governments across the world are interested in education technology and we are in a very good position."
Asked on the timing of the planned listing he added: "We have done this almost regardless of market conditions, we have been planning this for a long time."