Remember to have a title that describes what the key is about
Start with the most general
characteristics and progress to increasingly
more specific characteristics.
Use constant measurements, not ones that are highly
Use measurements when possible, avoiding descriptors like large
or small if possible.
Use characteristics that are found year-round, not seasonal
if at all possible (sometimes the point of a key is identifying
organisms based on seasonal
characteristics, such as flowers). If your key is seasonal,
indicate it in the title of the key.
Remember each time a couplet is completed, all organisms must
fit into one of the remaining categories or have been named.
Always provide two choices or a couplet.
After each choice in a couplet,
tell the user where to go or the name of the specimen.
When constructing a key, all of the items must fall into the
pathway that you are creating. For example:
Your key would be wrong, because Mrs. Donley is not a boy so
the pathway is invalid.
If we said we were making a key with shapes, and said that
a rectangle is a shape, and a square is a rectangle, then
an armadillo would not fit into the key at all.