Parallelogram
- quadrilateral (four sided figure)
- oposite sides parallel
<span>Rectangle
</span>- quadrilateral
- equiangular
<span>- right angle (90</span>° angle)<span>
Isosceles Trapezoid
</span>- quadrilateral
- pair of parallel sides
- called "trampezium" in the UK
<span>Square
</span>- regular quadrilateral
- equiangular
- right angles (90°)
The "one head and one tail" would be my best guess because you get one of each outcome, whereas the other two outcomes are two of the same outcome.