They take you upstairs into a room, explain what the position is like, ask you questions about what you feel you'll get out of the job and what you feel you'll be able to bring to the job.
I applied through other source. The process took 1 day. I interviewed at Exploratorium (San Francisco, CA) in Jun 2010
Interview
First you call on a certain day to get an interview. Suggested that you call early as possible and most likely during your school hours. It's first come first served for about 60 interview spots. You interview with two current explainers and then 1:1 with a supervisor. Simple questions such as what you are interested in at school, how you heard about the job, how you whould discribe yourself, what you think it the job is. No question is wrong. It's really more of a judge of your personality. If you make a good impression on the Explainer then you have a good chance of being hired.
It was pretty easy and mostly behavioral questions. I remember questions like "What does a High School Explainer do?", "How would your friends describe you", and they might also have you explain an exhibit in the museum depending on the interviewer. You get interviewed by High School Explainers first and then the program manager.
I applied online. The process took 1 week. I interviewed at Exploratorium (San Francisco, CA) in Aug 2019
Interview
This interview consists of two parts.
In the first, a fellow Explainer will ask you basic questions on your identity and intentions on coming here and then have you do a mock explanation of one of the exhibits. As intimidating as this sounds, it's not that difficult. The tone for this is pretty laid back. After all that, they will bring you up to fill out some basic paperwork.
The next is the interview with an adult employee. I got the manager. This interview is simple and standard, asking basic questions about your personality and why you intend to work there. As easy as that sounds, this one is something you cannot wing and answer on a whim. You should prepare to answer in such a way that aligns with what the Exploratorium wants as the more serious tone may throw your confidence off.