Richard Wood opened the scoring after six minutes of Saturday's Championship clash at Hillsborough and Jermaine Johnson doubled the hosts' lead six minutes later.
The game was all but over after just 34 minutes when Marcus Tudgay headed home and Darren Potter rounded off the scoring 13 minutes after the break.
"I thought they were exceptionally good," said Laws. "We worked on their weaknesses, which we exploited and I'm delighted that the game plan worked so well.
"It could have been 10. It was only the quality of their keeper, Joe Murphy, which kept the scoreline down.
"We've now got to put in performances like that away from home."
Laws was delighted with the work-rate of on-loan striker Luke Varney, saying: "He worked very hard and should have had a hat-trick.
"He links up well with Marcus Tudgay and they are going to be a thorn in the side of a lot of teams this season."
Scunthorpe manager Nigel Adkins admitted some harsh words had been spoken in the dressing room after the final whistle.
"The performance was a million miles away from what we expect at this football club and it wasn't good enough," said Adkins.
"We've had a chat in the dressing room and to a man, the players know they haven't performed. Their commitment, work-rate and effort wasn't there.
"The game was over for me after 10 minutes. We never put two passes together in the whole game and they beat us in every department.
"Congratulations to Sheffield Wednesday because they did very well. I'm not taking anything away from them."
Wood gave the home side a sixth minute lead, forcing the ball home from close range after Potter's corner was headed back by Tommy Spurr at the far post.
Johnson added a second, drilling a low shot past Murphy from just outside the area after collecting a loose ball.
Varney then had a shot saved by Murphy after finding himself through on goal following a defensive lapse.
Scunthorpe's only effort of note before the break fell to Paul Hayes who had a shot deflected wide.
The visitors had Rob Jones carried off on a stretcher before the half-hour mark after the big defender appeared to collide with a post.
After Murphy turned a James O'Connor shot wide, Tudgay made it 3-0, meeting Michael Gray's corner with a firm, downward header.
Tudgay spurned a great chance to add a fourth before the interval, putting a tame shot straight at Murphy after Scunthorpe were caught on the break.
Potter (58) rounded off the scoring, firing a thunderous 20-yard drive past Murphy.
It could have been an even more emphatic win for Wednesday, with Varney again failing to score after twice being put through on goal.