Sentence or Fragment?
and
example: I went to the park and played on the swings.
The automobile museum is closed but we can come back another day.
Not a run-on sentence.
but
example: I want to play outside, but it is raining.
or
example: Do you want a hot dog or a hamburger for dinner?
The whale looked huge Sara was amazed at it's size and length.
Yes, a run-on sentence
because
example: My team won the game because we had the most points.
My dog needed to go for a walk, so my mom asked if I could take him.
No, not a run-on sentence.
so
example: I have to do my homework, so I can play outside later.
The museum had old airplanes they looked small.
Yes, a run-on sentence.