This week on Brothers & Sisters, a divorced dad at Paige's school piques Sarah's interest. Looks like "The Science Fair" may mark her first foray into romance since Luc left!

Meanwhile, Justin finds the key to his learning challenges. It had better work, because he's on the verge of failing out, and his relationship with Rebecca has suffered too.

Also, as the sneak preview clip below shows, shady Simon is back in town after bailing on the wedding. It doesn't look like Nora has completely gotten over him, either ...

[video url="http://www.tvfanatic.com/videos/the-science-fair-sneak-peek/" title="The Science Fair Sneak Peek"] [/video]

What do you think this guy is up to? Did he try to steal Nora's money and will he do so again? Do you think Sarah is ready to date again? Will Justin pull it together?

For a closer look at Sunday's episode, which comes on the heels of last week's terrific "A Bone to Pick," click to enlarge episode stills from "The Science Fair" below ...

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.