I was pondering parts of speech and wondering if a
conlang could be designed around the idea of dividing
up words into a different set of parts of speech than
the set we are used to.

Here's a premilimary idea:

There are 6 parts of speech in the <whatever> (not
named yet)language.  These are:

A. Naming words: This class includes both nouns and
pronouns, (except indicative pronouns which are
considered to be adj/articles, see D. below.) which
are treated the same in <whatever>. Native naming
words tend to end in the letter "u".

B. Doing words: This class corresponds to the English
verb, although there are some differences in the way
they are used in <whatever>. They might be called
"half-verbs". (See Telling words.) Native doing words
tend to end in "o".

C. Telling words: These words stand before nouns and
specify the relationship between this noun clause and
the other clauses in the sentence. These words tend to
behave somewhat like verbs, but are not verbs. You
might think of a pair of words, one doing word and one
telling word, as making up the verb in <whatever>. The
doing words are really only half of a verb, with some
telling words making up the other half. Native telling
words tend to end in "a".

D. Changing words: include words classified in English
as adjectives, articles, possesive pronouns, and
cardinal and ordinal number words. These tend to end
in "i".

E. Gluing words: are words used to connect two phrases
and establish their relationship.  These relationships
include causative, if-then, and time ordering words,
to name just a few.  These words tend to end in "e".

F. Manner-of-acting words: correspond to English
adverbs. However, these words may also modify the
meaning of a Telling word. This class of verbs also
indicates such things as tense, mood and voice of the
word it modifies.  Native manner-of-acting words will
typically end in "y".

Maybe "doing words" and "telling words" are really the
same class making 5 parts of speech instead of 6. (?)

With SV order "John relinquish book moveto Mary
accept." where the "verb" comes in three separate
pieces, (reliquish/move to/accept) each piece
belonging ot the object most directly connected to the
doing.  [John relinquish] [book moveto] [Mary accept].

Since each half-verb can only take one object there is
no need to case mark anything.  I was thinking of
letting the article/adjective/pronoun (see D;
"changing word") carry the singular/plural distinction
so "this book" is singular and "these book" is plural,
but the noun doesn't change for plural, only the
"changing word" changes.

No words are ever inflected.  Verb tesne in indicated
by the manner-of-acting word (F).

I definitely need cool-sounding native terms for these
parts of speech.