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:
In rapidī radiō currūs fors Musca sedēbat;

Continuō clāmat iactanter Musca pusilla,

PROSE MACRONS. Here is the same text with macrons written out in prose word order:
Fors, Musca in currūs rapidī radiō edēbat; rotā prōgrediente, pulvis plūrima erat. Continuō Musca pusilla iactanter clāmat, "Ēn! equidem quantum pulveris ipse ciō."
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):
Fors, Musca in currus rápidi rádio edébat; rota progrediénte, pulvis plúrima erat. Contínuo Musca pusílla iactánter clamat, "En! équidem quantum púlveris ipse cio."
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.
In rapi·dī radi·ō cur·rūs fors· Musca se·dēbat;

Continu·ō clā·mat iac·tanter· Musca pu·silla,

IMAGE. Here's an illustration for the fable (image source) from another Aesop's fable about a boastful fly:

What follows is an unmarked version of the prose rendering to faciliate word searches:
Fors, Musca in currus rapidi radio edebat; rota progrediente, pulvis plurima erat. Continuo Musca pusilla iactanter clamat, "En! equidem quantum pulveris ipse cio."