Please give four visual images in the following passage: Willows whiten, aspens quiver,
Little breezes dusk and shiver
Through the wave that runs for ever
By the island in the river
Flowing down to Camelot.
Four grey walls, and four grey towers,
Overlook a space of flowers,
And the silent isle imbowers
The Lady of Shalott.

1) A calm and quiet place with willows (a type of flowers) and green grass in pleasant sunlight .

2) a seaside with trees like an island.

3) A river passing by with rocks and plants on its ends.

4) four long grey towers with very less windows with a garden with beautiful flowers along the way.

quite an interesting way to teach topic sentences, because the answer to this question is the best definition of a topic sentence that one can present, it is as if answering the questions taught you how to do it, this is some real teaching, it is terribly well-done.

the topic sentence in this paragraph is:

topic sentences writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea.

which incidentally tells you what a topic sentence should be.