In addition to being an exercise on tense, number, and prepositional phrases, this is a challenging exercise in what writing teachers call "invention." Students will need to "invent" the details of identity and extension in time and space. Weak writers often omit these details, and this omission accounts for much of the weakness in their writing, both in terms of details and in terms of main-clause length, a major yardstick of syntactic maturity.
     Note that "identity" and "extension in time or space" are the first two of Hume's three basic logical categories, so this is also an exercise in basic logic.

1. Six hungry hawks were chasing a little bird (DO) {across a silken sky} [Adv.

(where) to "were chasing"] {of blue} [Adj. (identity) to "sky"] {on a mild March 

morning}  [Adv. (when) to "were chasing"].  [Past, plural]
 

2. The white sails {of the frigate} [Adj. (identity) to "sails"] were flapping {in the

wind} [Adv. (where) to "were flapping"] {during the storm} [Adv. (when) to "were 

flapping"].  [Past, plural]
 

3. Will the human mind understand the meaning (DO) {of love} [Adj. (identity)

to "meaning"] {in every corner} [Adv. (where) to "will understand"] {of the world} 

[Adj. (identity) to "corner"] {in the future} [Adv. (when) to "will understand"]? [Future, 

singular]
 

4. {Throughout their lives} [Adv. (when) to "hurts"], the evil {of men's hearts} [Adj.

(identity) to "evil"] hurts themselves (DO) {in many different places} [Adv. (where)

to "hurts"]. [Present, singular]
 

5. {For days and days} [Adv. (how long) to "howls"] the tempest howls {over the

cold waves} [Adv. (where) to "howls"] {of the North Sea} [Adj. (identity) to "waves"].

 [Present, singular]
 

6. {In the Senate} [Adv. (where) to "will discuss"], politicians {of both parties} [Adj.

(identity) to "politicians"] will discuss the proposal (DO) {for many days} [Adv. (how

long) to "will discuss"].  [Future, plural]