All dance is, to a certain extent, improvisation. A performer never knows what's going to happen onstage, and has to be ready for anything. But usually there is choreography to fall back on – set steps that have been rehearsed to within an inch of their life.

But what would happen if there was no formal choreography? What would happen if a dancer went onstage and used that first vulnerable, foot-lit moment onstage as their guiding muse?

If you're curious, come to Danceworks this weekend and find out.

Spur-of-the-moment genius is what "Serendipity," the company's winter performance, is all about. The show will feature pieces by guest choreographer Emma Draves as well as Danceworks staff choreographers Kim Johnson-Rockafellow, Dani Kuepper, Liz Tesch and Joelle Worm.

So how exactly do you go about choreographing spontaneity?

"It's pretty structured," says Worm, who created the piece "In Passing" for the show. "The dancers have a lot of instructions that they have to attend to at all times throughout the performance. But I have never said 'tendu left' or 'pique right' – no. The dance steps themselves are not set, but the structures the dancers have to fulfill are set from night to night."

"Structures" refers to the general game plan for each performance - the theme, whether the dance takes place on a diagonal or vertical line and what is expected of each dancer. As the choreographer, these are things that Worm is in charge of. "In Passing" demands that the dancers mimic one another, so it's up to the first dancer onstage to set the tone - and for the others to be aware and receptive of that communication, all while putting on a show.

But Worm does not send her dancers out on stage with nothing more than a warm-up and a friendly "Break a leg, we'll see what happens." She and her team have been rehearsing intensively in the weeks leading up to "Serendipity," exploring possibilities, building trust and creating dialogue. It's a far cry from winging it.

It's a lot like the process of an improv comedian, she says.

"We rehearse options and we find out what works. You find out it works to, like, repeat some things but not everything, or change level at this midpoint to make a strong midpoint. You rehearse all the options that could exist and then in performance, it is what it is. You work on the skills."

Important skills include trust and ability to communicate. There has to be a solid relationship onstage and off between the dancers and their choreographer - and between the dancers themselves.

It's a process that requires "a lot of ensemble-building," Worm says. "You do a lot of awareness-building. We talk about being inside the dance and having the outside eye of the dance. So you are constantly thinking about what might the audience be experiencing right now based on what I'm doing and in relationship to that dancer and this dancer, so you're shaping all these things in the moment."

Worm grew up studying at Danceworks before pursuing a successful performance career in New York City, where she discovered the artistic style of Richard Bull, a jazz pianist and modern dance choreographer who passed away in 1998.

"He took principles of improvisation from jazz music and applied them to dance. The idea is not to run though the dance a million times. That's not going to do it. You need to rehearse the skills," she said.

She never identified herself as a traditional choreographer, and is drawn to the improvisational side of movement because of its physical and intellectual demands.

In 2004 she became involved in De Facto Dance in New York, a company founded by former members of the Richard Bull Dance Theatre. She still collaborates with the company even after returning to Milwaukee in 2010.

Worm says that an audience should never be able to tell that a dance performance is improvised.

"When the dancers are working really well together, they're remembering what they've done (before) they're bringing things back, they're developing ideas, it should look like set work," she said. "As a dancer, it speaks to me because I get to be both a creator and a communicator at the same time. Literally, the first time I saw De Facto, I was stunned. I was like, 'What does this mean, this isn't set?' Because you really couldn't tell, with how engaged and sure of what they dancers were doing."

The result of improvisational dance is that no two nights are the same. But ideally, there should be a common link between all the performances, and repeat audience members will have the treat of viewing two different interpretations of the same theme.

"The dance is always in the same world," Worm says. "It's not drastically different every time. But it's different decisions that are made, different relationships that happen."

Worm says that fellow Danceworks performer Melissa Anderson has said that improvisational dance requires using your "dolphin brain."

"One side is thinking and one side is dancing," she laughs. "The other day in rehearsal, Melissa said, 'I just realized I've been improvising my whole career.' And I'm like, 'Exactly! It's performance.'"

"Serendipity" runs at Danceworks, 1661 N. Water St., Feb. 1-10. Visit the website for ticket information.