Firstly, the festival can start with a 30-minute discussion where groups of students can exchange and share what they have been exposed to recently, expressing themselves freely. 

【翻译】首先，这个节日可以从一个30分钟的讨论开始，各组学生可以交流和分享他们最近接触到的东西，畅所欲言。

be exposed to：形容词短语。意为“暴露于；感染于；面对于”，引申为“接触到；学到”。