The Lincolnshire club sacked Brian Laws following their FA Cup derby defeat to Grimsby Town last week and have now won both games under caretaker managers Russ Wilcox and Tony Daws after their resounding victory against nine men at Spotland.
Keith Hill's Rochdale had only lost once at home in League Two ahead of Scunthorpe's visit, but red cards for skipper Olly Lancashire and Jack O'Connell proved to be costly as Niall Canavan, Sam Winnall, Jimmy Spencer and Dave Syers struck for the visitors.
That victory moves Scunthorpe up to sixth in the table, while Rochdale slip out of the automatic promotion places and are replaced by Phi Brown's Southend United, who were 2-1 winners at Portsmouth courtesy of goals from Will Atkinson and Barry Corr.
Oxford United remain top despite a goalless draw with Newport County and Chesterfield missed the chance to replace them after being held by the same scoreline at home to bottom club Northampton Town.
Just three points separate the top seven and Fleetwood Town were another side who could have gone top, but they were beaten 2-0 at in-form Accrington Stanley.
A Danny Webber penalty and a Kayode Odejayi strike in the last 15 minutes made it three consecutive wins for James Beattie's Stanley side, who are now five points above the relegation zone.
Burton Albion occupy the final play-off spot after Billy Kee scored the only goal of the game at home to Mansfield Town.
Torquay United remain second bottom after drawing 1-1 at home to Plymouth Argyle, with Elliott Benyon putting them in front after six minutes and Reuben Reid levelling from the penalty spot three minutes later.
Struggling Bristol Rovers held Cheltenham Town to a goalless draw at Whaddon Road, while York City and Morecambe also failed to muster a goal between them.
On-loan striker Daniel Nardiello gave Bury a much-needed 1-0 win over Hartlepool United. Wimbledon and Dagenham and Redbridge drew 1-1 at Kingsmeadow, while Wycombe Wanderers and Exeter City also drew 1-1.
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