DS calls it a trapezium and he's just coming up to 3.
Australia is one of the only western countries that teach but dont always use correct geometric and mathematical terms.
When I started Tupperware it was one of the first things I looked up so I'd know the correct name (yeh I know Im a geek lol)
if you really want a discussion on paralellagrams, rhombi, squares and rectangles I'm your geek, .

Astrolady - you listed 11 shapes and I know the regular shape-o only comes with 10, so maybe its different, I will check tonight.