B/W to color, color to B/W

"Black and white to color, color to black and white" was the title of the assignment.
I decided to take pictures of all details of a color analogical printer that the department was going to sell.
I took the pictures with a digital camera and printed them at a printshop.
When I picked up the pictures I found some sheets (same format as the pictures, 10 x 12.5 cm) with some graphical black and white lines and rectangular.
I asked the clerk what it was and he said he picked it from the digital printer in the moment that my pictures were delivered.
It was a mystery also to him.