Three right angled triangles are all that is needed to create one of these Flying Geese units (or patches.) The largest triangle piece is considered to be the "geese" piece -- (why it is not called a "goose" piece is beyond me). The other two identical triangles are considered to be the "sky" pieces.
Flying geese units are probably the third most commonly used patches in quiltmaking -- following the square and the half square triangle.
Thunder and Lightning
Toad in the Puddle
Wheel in the Road
Winged Four Patch