Sentence Fragments vs Complete Sentences

Is the following a sentence or a fragment?

"While I walked home from Jerry's house."

Is the following a sentence or a fragment?

"My mother, the skating champion."

Is the following a sentence or a fragment?

"It sat."

Is the following a sentence or a fragment?

"Under the bench."

Is the following a sentence or a fragment?

"On the other hand, if you want a doughnut."

Is the following a sentence or a fragment?"The lamp on the table, swinging from it's cord, near the mousetrap."

The turtle slowly crawled across the beach.

Yesterday when I got off the school bus.

My friend Sheila and I saw a brown toad hopping on the sidewalk.

Yelled and screamed when she saw it.