Yellowstone National Park was founded in 1872. It covers nearly 3,500 square miles of wilderness and contains many unusual geological features. The park is home to large populations of mammals, including bison and elk. For years, the elk population grew rapidly until the reintroduction of wolves to the park in 1995.1. Yellowstone National Park was founded in 1872. 2. It covers nearly 3,500 square miles of wilderness and contains many unusual geological features.
3. The park is home to large populations of mammals, including bison and elk.
4. For years, the elk population grew rapidly until the reintroduction of wolves to the park in 1995.

8 ish depending on the what grade

sentences vary by structure as well as by function. there are compound, complex, and compound-complex sentences.

simple sentence

i like to read.

a simple sentence has one independent clause.

compound sentence

i like to read, and i also like to write.

a compound sentence includes more than one independent clause, connected by a coordinating conjunction (and, but, for, nor, or, so, or yet).

complex sentence

i prefer to read books that are bestsellers.

a complex sentence includes one independent clause and one or more dependent clauses. (a dependent clause is one that cannot stand alone.) types of dependent clauses include relative clauses (i kicked the boy who pinched me), adverb clauses (i am going home now because i have a curfew), and noun clauses (i don't know what to do next).

compound-complex sentence

although i prefer to read current bestsellers, i do like to read old agatha christie mysteries, and i also like some 20th-century science fiction.

compound-complex sentences take a bunch of clauses (multiple independent clauses, and one or more dependent clauses) and toss them together like a salad. although these sentences take practice to write in a grammatically correct fashion, they can hold a tremendous amount of meaning, and are common in academic writing.