Why is the main character in "The Revolt of the 'Mother." considered a round, dynamic character?

The main character is round and dynamic
because she is fully developed and undergoes a
change.

A round character is one where many
traits are described.  We know that Sarah Penn is stubborn, intelligent, articulate, and
can think divergently.

When looking at the barn and the
house, Sarah feels frustrated.  She sees that the barn is much bigger and
nicer.

The
house, standing at right angles with the great barn and a long reach of sheds and
out-buildings, was infinitesimal compared with them. It was scarcely as commodious for
people as the little boxes under the barn eaves were for
doves.

The barn is where her
husband puts his priorities.  He does not even tell his wife that he is building another
barn.  This infuriates her.  While telling her daughter that she will someday learn that
she will never be the equal of men, she is clearly irritated and
frustrated.

A dynamic character is one that undergoes a
change.  Sarah Penn is a good housewife at the beginning of the story.  She listens to
her husband and fulfills her role as a good wife, but when her husband breaks his
promise to build her a nice house and instead decides to build himself a barn, she
revolts.  This demonstrates her potential for change.

When
her husband starts building the barn, Sarah finally confronts
him.

 I ain't
never complained, an' I ain't goin' to complain now, but I'm goin' to talk
plain. 

When that does not
work, she moves into the barn.  Even when the minister comes, she holds her ground.  She
does not back down, and demonstrates a new strength equal to men, showing her growth as
a dynamic character.