LAWRENCE, Kan. (AP) - Sam Richardson, who had not even attempted a pass all year, threw for 250 yards and four touchdowns Saturday night, sparking Iowa State past Kansas 51-23 and handing the Jayhawks their 20th consecutive Big 12 loss.

Richardson led the Cyclones (6-5 overall, 3-5 Big 12) to touchdowns on four straight possessions in the second quarter while taking a 38-17 lead. The redshirt freshman, virtually overlooked all year in the Cyclones' jumbled quarterback picture, had previously seen only mop-up duty in one game.

While going 23 for 27, Richardson spread his completions around to 12 different receivers. Six different Cyclones scored touchdowns.

For Kansas (1-10, 0-8), the final home game of the year sent a bedraggled class of seniors out on the same sort of sour note which has characterized their entire collegiate careers.

The fourth- and fifth-year seniors came aboard just as the Mark Mangino-coached Jayhawks were winning two straight bowl games for the first time in school history. The long-struggling program seemed headed for the heights. But after starting the 2009 season 5-0, the Jayhawks lost their next seven and now, counting this lopsided loss to Iowa State, have dropped a stunning 36 of 42 games under three head coaches.

Kansas will need to win at West Virginia in its season finale on Dec. 1 to avoid its worst season since the 1988 Jayhawks finished 1-10.

It's also a bitter entry into the Big 12 for Kansas coach Charlie Weis, who announced at midweek that he would pay the $3 charge for anyone who wanted to buy a student ticket and come to the game. Officials said it would be several days to know how many took him up on his offer. But it appeared only a few hundred did.

Richardson replaced starter Steele Jantz on Iowa State's third possession and immediately engineered a 10-play, 89-yard drive connecting, with Josh Lenz for 30 yards and setting up Jeff Woody's 11-yard touchdown run for a 10-7 lead. Lenz also had a 14-yard touchdown catch in the fourth quarter.

Tony Pierson rushed for 89 yards for Kansas, including a 55-yard touchdown run in the second quarter, and caught a 37-yard scoring pass from Dayne Crist in the fourth. But after his 55-yard score, Iowa State answered immediately with Richardson's 11-yard scoring pass to Albert Gary.

Durrell Givens recovered James Sims' fumble on the Jayhawks' next possession, and five plays later Richardson connected with a wide-open Aaron Horne on a 30-yard scoring play, making it 24-14.

The lead went to 31-14 a few minutes later when Richardson, following Woody's 43-yard run, dived over from the 1.

A 20-yard pass to Ernst Brun, capping a six-play, 57-yard drive, completed the second-quarter blitz and put Iowa State on top 38-14.

Edwin Arceo kicked three field goals for the Cyclones, including a 51-yarder in the third quarter.