The deadline for proposals for the Cambridge Science Festival is Thursday, city councillor Henrietta Davis reminded in a Monday e-mail.

“Now’s your chance! Submit a proposal to run a program or host an event,” went the text of the e-mail:

Programs may include lectures, performances, activities for families, exhibits, tours, debates, workshops or creative new ideas we’ve never imagined. We’re looking for ideas that celebrate science, technology, engineering and math in ways that combine spirit, interactivity and audience appeal.

The event, the fifth, is scheduled to run April 30 through May 8.

Last year’s included an 89-booth science carnival, treasure hunt, game shows, multimedia contests, science-themed theater, five-minute lectures and brown-bag lunches with Nobel laureates — dozens of events, most free, over nine days.