1.
Sound
Loud sounds can attract people's attention. It's been use for street performances, when people hear sound, they will want to see what's happening.
2.
Example
To get others to be active, the performer can choose one or two friends to start an example, and if people are interest, they will start to play theirselves.
3.
Question
Start with asking some questions that relate to the topic, and people can answer as group or individual, then just talk into the topic, and introduce more content and details.
4.
Be Active
In order to get others to be active, the performer herself/himself needs to be active first, so she/he can attract other people's attention, and then he/she can starts to play with others, so the viewers become performers.
