It's a familiar story:
It started with a goal.
Jack and Jill went up the hill to fetch a pail of water.
Then tragedy struck.
Jack fell down and broke his crown.
Sometime gymnastics pays off.
Jill came tumbling after.
Yes, I used an alternate meaning for
tumbling than the original story
intended, but you get the idea, and I saved Jill's life by letting her
avoid cranial trauma and land on her feet at the bottom of the
The topic sentences did a good
job of preparing the reader for the action without giving away the
story. That is the same effect for which you need to strive..
If your instructor doesn't ask for topic sentences, then you can suit yourself. Sometimes, they won't help.