My kids do a variation of the tile project, but before I turn them loose with the two color HPDE, I buy sheets of 1/8"masonite. I rip them down to 5-7/8" squares on the table saw and let them use this to “practice” using the default settings for MDF and a 1/16th mill.They can carve both sides of the masonite if they limit the cut depth to about 0.05". I also let them paint the squares and coat them well with polycrylic. This gives them something a bit closer to the two color plastic and gives them practice using paint, cleaning brushes, etc. I let them have the masonite panels for free, but they have to reimburse me when they are ready to move on to the HDPE.
I also cut the masonite into other sizes as long as they are (common factors - kerf width) of 48 and 96, so 7-7/8", 11-7/8", and 15-7/8" masonite squares are always in my materials inventory.
Masonite squares are also good to keep around for kids to make scroll saw projects, and usually I have a few who realize they can digitize their scroll saw patterns and cut them on the x-carve.
I had one kid who found Steve Ramsey’s Christmas shadow box project, washed his PDF through Inkscape and cut the patterns on the X-Carve…this was before Easel’s image trace tool was well understood.
At the beginning of our X-Carve adventures, I was very fussy about detailed lesson plans for an X-Carve project. But now that I have a “museum” shelf full of X-carve-d items for kids to look at, I just concentrate on making sure they can use the machine safely without breaking it and spend more of my time teaching design development and engineering processes. X-Carve is now just one of the shop tools and I no longer require "an x-carve projec"t, instead, I require a project that contains components that were made on the x-carve, and the 3d printer as well as the band saw, scroll saw, drill press, sanders, hand tools etc.
One piece of advice for any school considering an X-Carve. I would strongly recommend buying one of the small ones first. I have two machines, and 99% of the things we make would fit just fine on the small machine. I probably WON’T do this, but I have given serious consideration to cutting the 1000mm machine down. Truth is, I would rather have 2 500mm machines than a single 1000mm machine.