NoDictionaries.com: You can find the word list for this fable online, and use it interactively (here are some tips on how to make best use of the tool).
READ OUT LOUD. Choose which marked text you prefer to practice with - macrons or accent marks - and read the text out loud until you feel comfortable and confident. Then, try reading the unmarked text at the bottom. It should be easy for you after practicing with the marked texts. :-)
MACRONS. Here is the text with macrons:
In prātō quondam rāna bovem cōnspēxit. Tācta invidiā tantae māgnitūdinis, rūgōsam īnflāvit pellem, et fīliōs suōs interrogāvit, utrum lātior quam bōs esset. Illī negāvērunt. Rūrsus intendit cutem maiōre nisū et similī modō quaesīvit, uter maior esset. Illī respondērunt bovem esse maiōrem. Tum, dum rāna vult validius sēsē īnflāre, ruptō iacuit corpore.
ACCENT MARKS. Here is the text with ecclesiastical accents, plus some color-coding for the words of three or more syllables (blue: penultimate stress; red: antepenultimate stress):
In prato quondam rana bovem conspéxit. Tacta invídia tantae magnitúdinis, rugósam inflávit pellem, et fílios suos interrogávit, utrum látior quam bos esset. Illi negavérunt. Rursus inténdit cutem maióre nisu et símili modo quaesívit, uter maior esset. Illi respondérunt bovem esse maiórem. Tum, dum rana vult valídius sese infláre, rupto iácuit córpore.
UNMARKED TEXT. Here is the unmarked text - after practicing with the marked text that you prefer, you should not have any trouble with the unmarked text:
In prato quondam rana bovem conspexit. Tacta invidia tantae magnitudinis, rugosam inflavit pellem, et filios suos interrogavit, utrum latior quam bos esset. Illi negaverunt. Rursus intendit cutem maiore nisu et simili modo quaesivit, uter maior esset. Illi responderunt bovem esse maiorem. Tum, dum rana vult validius sese inflare, rupto iacuit corpore.
IMAGE. Here is an illustration for the story (image source), from a Renaissance edition of Aesop:
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