*cracks knuckles*
Here's all the old machines still in daily use in my classroom.
On my desk I've got two. My main machine at school is a 27" 2010 iMac (2.93GHz quad i7, 256GB SSD, 32GB RAM), and it is a
beast of a machine. I adore this computer. To its left is an early 2008 20" iMac (2.4GHz C2D, 6GB RAM, 180GB SSD) that's been in my office for the last four years as my main machine in there, though it's recently been replaced and repurposed on my desk in the main classroom as a third display for monitoring the student computers. Under the ACD to the right is a 2014 mini (2.6GHz i5, 8GB RAM, 256GB SSD) that's hooked up to the projector. I remote into it from other computers to control what goes on the projector.
Of course, I've got a bunch of stickers and whatnot on the back. Gives it a bit more personality in a location where the back will always be seen
Over a bit from my desk is a 2011 11" Air (1.6GHz i5, 2GB RAM, 128GB SSD) that I use to remote into my server, projector machine, and door computer to control them while I'm presenting to the class. This laptop used to be my main school laptop for several years (I currently use a 2015 13" MBP), so it's great to keep it in service.
Over by the door I've got a pair of iMacs. The 2006 20" (2.16GHz C2D, 3GB RAM, 160GB HDD) used to be my main announcement/seating chart machine, though it's been replaced this year by the early 2008 24" (2.8GHz C2D, 4GB RAM, 64GB SSD) to its right. This was mostly because the 2008 can run newer versions of OS X (it's currently running Mojave) that can sync with my OneDrive. The 24" is on all day, every day with announcements and/or my seating charts.
Up above the two iMacs is my classroom server, a 2009 Mac mini (2.0GHz C2D, 8GB RAM, 120GB SSD). I use it for file storage, Time Machine backups for all the other Macs, and to run some legacy software, particularly my lab management software.
In my office I have the machine that served as my main machine for the past three years, a 2010 21" iMac (3.06GHz i3, 16GB RAM, 256GB SSD). It's used for pretty much the same stuff as my main machine when I want a change of scenery at lunch or on my planning period.
Those are the core of my production machines in my classroom! Here's a long shot where you can see my desk, the Air on its cart, and the iMacs off in the distance. I've also got a few much older machines in various stages of refurbishment scattered around my classroom