Example Binomial Key 1: Identifying a Bunch of Human-created Stuff
1.a. Mostly or entirely metal. Possibly sharp-pointed, possibly functioning on the principle of an inclined plane. Not entirely penetrated entirely by small, round holes. Go to 4.
1.b, Not metal, not functioning on the principle of an inclined plane. Plastic; entirely penetrated by small, round holes. Go to 2.
2.a. Penetrated by four small, round holes. Go to 3.
2.b. Penetrated by two small, round holes: White button.
3.a. Color uniform and dark: Black button.
3.b. Color tan to brown, somewhat mottled as opposed to uniform: Brown button.
4.a. Functioning on principle of inclined plane (long axis cut in spiral grooves). Go to 5.
4.b. Not functioning on principle of inclined plane. Go to 7.
5.a. Not sharp-pointed: Bolt.
5.b. Sharp-pointed. Go to 6.
6.a. Blue in color; length > 3cm; cut for straight screwdriver: Blue screw.
6.b. Copperish in color; length < 2cm; cut for Phillips Head screwdriver: Brass screw.
7.a. Yellow-brass in color; capable of holding some water: Go to 8.
7.b. Not as above. Go to 11.
8.a. Hole diameter < 6mm; 1 letter on solid end: .22 brass.
8.b. Hole diameter > 7mm; > one letter on solid end: Go to 9.
9.a. “Cylindrical” part tapered; hole diameter < 9mm: .303 British.
9.b. Hole diameter > 10mm; hollow part not tapered: Go to 10.
10.a. Height approx. 2X hole-diameter: .45ACP.
10.b. Height > 3X hole-diameter: .45 Colt.
11a. A very short, copper-colored cylinder with words on both sides: Penny.
11.b. If cylindrical, then length > diameter. Go to 12.
12.a. Sharp-pointed; fasteners that hold by penetration; if cylindrical, then not folded perpendicular to long axis. Go to 13.
12.b. Fasteners that hold by non-penetrating compression, typically applied to sheets of paper; folded > once, w/ folds perpendicular to long axis. Go to 14.
13.a. Can lie stable in > 1 position; sharp, penetrating linear shaft attached to approximately disk-shaped “head” that is > wider than shaft; longest dimension < 2cm: Thumbtack.
13.b. Not as above; longest dimension > 2cm: Small nail.
14.a. Dimension as folded < 2cm: Small paper clip.
14.b. Dimension as folded > 3cm: Large paper clip.
Example Binomial Key 2: A Merely Identify-‘em Key to Last Week’s Lab Critters
1.a. In a peanut butter jar. Go to 2.
1.b. Not in a peanut butter jar. Go to 4
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2.a. Distinct longitudinal stripes; tail much longer than head-body: 3-lined salamander.
2.b. Not as above. Go to 3.
3.a. Mostly dark, without white dorsal blotches: Slimy salamander.
3.b. Chunky; distinct white dorsal blotches: Marbled salamander.
4.a. Dominant colors red and black and yellowish-white: Mexican milksnake.
4.b. Colors otherwise. Go to 5.
5.a. Longer than 1.1m: Pinesnake
5.b. Shorter than 0.9m: Go to 6.
6.a. With ear openings and eyelids: Eastern glass lizard.
6.b. Lacking ear openings and eyelids: Speckled kingsnake.
Example Binomial Key 3: Evolutionary-Trajectory Key to Last Week’s Lab Critters
1.a. Not producing amniotic eggs; skin lacking scales. Go to 2.
1.b. Producing amniotic eggs; skin obviously scaled. Go to 4.
2.a. Having lungs; lacking labio-nasal grooves. Marbled salamander.
2.b. Not as above. Go to 3.
3.a. Lacking aquatic larvae; large ossified 2nd basibranchials: Slimy salamander.
3.b. With aquatic larvae; large ossified 2nd basibranchials: Three-lined salamander.
4.a. Mandibular symphasis fused; ear openings & movable eyelids: Eastern glass lizard.
4.b. Mandibles connected by ligament (not ossified); no ear openings or movable eyelids. Go to 5.
5.a. Rostral scale extends upward between internasal scales; scale-rows usually > 27; ventrals somewhat angular; rostrum somewhat modified for burrowing; dorsal scales with rough appearance: Pinesnake
5.b. Otherwise. Go to 6.
6.a. Last two maxillary teeth usually longer and stouter than the preceding ones: Mexican milksnake.
6.b. Last two maxillary teeth usually not longer and stouter than preceding ones: Speckled kingsnake.