READ OUT LOUD. Choose which marked text you prefer to practice with - macrons in verse form, or macrons in prose order, or accent marks in prose order, or focusing on the meter. You will find materials for all of these options below. :-)
VERSE MACRONS. Here is the verse text with macrons:
Quercus, et adversāns illī contendit Harundo,

Tunc quamvīs Quercū quod mōbilis esset ad auram

Tempore sed parvō post dīruta turbine Quercus

At variē flectēns sē ventīs cessit Harundo,

Laudandī potius sunt, quī concēdere nōrunt,

Nōveris esse Deō, convellat ut ardua, mōrem,

PROSE MACRONS. Here is the same text with macrons written out in prose word order:
Quercus contendit et Harundo illī adversāns, utraque refert sē magis praestantem esse. Tunc quamvīs Quercū obiciente quod ad auram mōbilis esset, Canna lubēns modesta tacet. Sed tempore parvō post Quercus dīcitur turbine dīruta et rāmīs suīs fracta fuisse. At Harundo cessit, ventīs variē sē flectēns, ea hāc mōbilitāte frangī nōn potest. Laudandī potius sunt, quī concēdere nōrunt, quam fortēs quī prae sē superāre parant. Nōveris mōrem Deō esse ut ardua convellat, quō premente, summa diū stāre nōn valent.
STRESS (ACCENT) MARKS. Here is the prose text with accents, plus some color-coding for the words of three or more syllables (blue: penultimate stress; red: antepenultimate stress):
Quercus conténdit et Harúndo illi advérsans, útraque refert se magis praestántem esse. Tunc quamvis Quercu obiciénte quod ad auram móbilis esset, Canna lubens modésta tacet. Sed témpore parvo post Quercus dícitur túrbine díruta et ramis suis fracta fuísse. At Harúndo cessit, ventis várie se flectens, ea hac mobilitáte frangi non potest. Laudándi pótius sunt, qui concédere norunt, quam fortes qui prae se superáre parant. Nóveris morem Deo esse ut árdua convéllat, quo preménte, summa diu stare non valent.
ELEGIAC COUPLET METER. Below I have used an interpunct dot · to indicate the metrical elements in each line, and a double line || to indicate the hemistichs of the pentameter line.
Quercus, et ·adver·sāns il·lī con·tendit Ha·rundo,

Tunc quam·vīs Quer·cū quod· mōbilis· esset ad ·auram

Tempore ·sed par·vō post· dīruta· turbine· Quercus

At vari·ē flec·tēns sē· ventīs· cessit Ha·rundo,

Laudan·dī poti·us sunt,· quī con·cēdere· nōrunt,

Nōveris ·esse De·ō, con·vellat ut ·ardua,· mōrem,

IMAGE. Here is an illustration for the story from the 1574 edition of Osius:
What follows is an unmarked version of the prose rendering to faciliate word searches: Quercus contendit et Harundo illi adversans, utraque refert se magis praestantem esse. Tunc quamvis Quercu obiciente quod ad auram mobilis esset, Canna lubens modesta tacet. Sed tempore parvo post Quercus dicitur turbine diruta et ramis suis fracta fuisse. At Harundo cessit, ventis varie se flectens, ea hac mobilitate frangi non potest. Laudandi potius sunt, qui concedere norunt, quam fortes qui prae se superare parant. Noveris morem Deo esse ut ardua convellat, quo premente, summa diu stare non valent.