Last night I had to stay in the lab until almost midnight, actually around 11:45. This time the PI put me in charge instead of the professor who was stuck in a meeting. I'm a TA, 25, and my friend and I take turns watching the usual shifts — we cover the evening to late night, like six hours or so.

A group from the uni next door had arranged to come see our system. They arrived after 7pm — one professor and maybe six students. They were taking photos and greeting us. I smiled, showed them around the benches and equipment, explained the steps I actually do, demonstrated and let them try in turns. I was jotting notes with a black gel pen. The kids asked a lot of questions, and I tried to answer in detail because I teach this stuff the most.

I was just doing my TA role, you know?

Then out of nowhere the PI messages on LINE saying “Make the students take a break and prepare a formal presentation.” What even is that? Why change things on the spot like that? And asking for 10 minutes to prepare slides — is that even reasonable? My friend and I scrambled to collect papers, open a laptop and threw together some slides in about 10 minutes. I felt a bit lightheaded because I wasn’t prepared to be the main presenter. Honestly I'm not used to it, it was my first time speaking seriously this shift.

I was a little shy during the demo, stumbled sometimes, but I tried so hard. Really tried. And when I finished, instead of a bit of encouragement, the PI complained, like “If you face this kind of situation you must manage it immediately, act professional.” Um... I'm a student doing a part-time job, not a PR person on call 24/7. What made it worse was the PI said the visitors thought I looked unprepared, then had another person come finish the presentation — even though I had just finished explaining. It felt like they pulled my role away midstream. I felt stripped of responsibility on the spot.

Confused. Upset.

Funny thing: in the morning the PI had told me to take care of things, but as soon as outsiders showed up they just changed my role without warning. Like I was a test subject put in a show outfit for a bit, and if anyone praised it they'd hand the credit to someone else. Right? I don't want to overthink but I sort of wonder if the PI is biased, or if my outfit wasn't good enough. Ugh. I dressed by the lab rules, not anything provocative.

Sorry typing on my phone, forgive any typos haha. I want to ask you folks: should I talk to the PI directly and politely ask them not to change my role like that in front of visitors? I really want actual advice, because I want to do my job well, but it’s tiring feeling like I'm not seen as part of the team when real things happen. I'm scared bringing it up will make the atmosphere worse, but I also want to stand up for myself a bit T_T