They tried to bait and switch me

I don’t sub in middle school unless it is a SPED class. I like working with the smaller groups of kids and the kids are really sweet most of the time. Today is the Friday before Thanksgiving break. They’re off Monday-Friday next week. I came in early and the secretary says “Hi!! We have you in 6th grade science today instead of the sped room. How do you feel about that?” My response was “I’m really not comfortable in 6th grade classes. I’m so sorry”. I feel like I irritated the secretary but why should we feel like we have to put ourselves in uncomfortable positions to make them happy? I don’t make enough money to be harassed by 6th graders for 7 hours.