Today, one of my coworkers "tasked" me to eat with the new trainee (so that she won't eat alone since my colleague wasn't available for lunch).
I wanted this person to feel comfortable so I started to ask questions about her studies (what are you studying, how long will your internship be, what do you want to do after that, etc...). She seemed open to the conversation and was giving some details not asked for when answering.
Other coworkers were starting to arrive for lunch and the conversation slowly moved away. I noticed that the new trainee wasn't taking part in the conversation and I assumed she needed more time to feel comfortable around us.
Assuming it's possible, how could I have made her more comfortable around us? Maybe even comfortable enough that she would have joined the conversation?
Notes and clarifications
This new trainee was in the center of the tables, where all the conversations happened, so that wouldn't have been an issue.
We were talking about food and other subjects where everyone can participate (no specific knowledge needed).
The trainee was given a tour the first day (today was her second) and people said their name to her (and a brief description of what their work is) but she probably didn't remember most of them (unless she has a very good memory for this kind of things).