But of course I'm psychic!

Right now everyone is teaching Forces and Motion. This means a lot of dynamics trolleys, masses, dataloggers and light gates are getting moved around from lab to lab.

Yesterday one of my teachers had ordered the full kit, plus the air track for a demo. I started getting it all set up in his lab during lunch break. He was sat at his desk eating his sandwiches and chatting to a student while I carried in trays of stuff and set them out on the side bench, before fetching the air track.

It must've taken me a good 5 minutes to get it all in place, at which point he piped up and said 'Oh, by the way Labtech666, I'll only need the air track today'.  'I thought you ordered the trolleys too' I replied.
'Yes I did', he said, 'but they don't get such good results so I decided to just do the air track demo'.

Fair enough, but wouldn't it have been nice if he'd said something BEFORE I started shifting loads of kit into his lab. He watched me do it for crying out loud!
Am I meant to be psychic and just know when they've changed their mind about a practical? Or maybe I should ask them before every lesson just to check.
Or, here's a novel idea, maybe they could have the courtesy to let me know what's going on.
Yeah, right!