A bunch of Barlows, more than likely single blades, any one of witch cost a hole bunch more than all the two blade Barlows that I have, combined?
Oh, and the board they are on is weathered, with no nail or screw holes visible.
I haven't been in a classroom in 46 years. I forget what a leaning rectangle is called. Surprisingly, I've never had to use that word, or deal with whatever it is, in all the jobs I had between 1969, and when I was forced to retire for health reasons three years ago. Not even when I was a mobile and fabrication welder from 1974 or 1975 to 1978. (yeah, sometimes I wonder if leaving that profession was a "wise" decision.)
Shockingly, I have not come across or had to deal with one of them things since I retired, either.
EDIT: An BING! search says a leaning rectangle is called a "Parallelogram".