Ecce Romani (pronounced EK-kay ro-MAH-nee) is both a famous Latin textbook series and a grammatical showcase.
The Ecce Romani series (originally Scottish, 1970s; Pearson/Prentice Hall editions widely used in US/UK schools) employs a continuous narrative about a Roman family (the Cornelii) to teach grammar inductively. The title phrase appears in early chapters as the family encounters Roman soldiers.
For students: ecce is a "demonstrative particle" — it doesn't conjugate, doesn't decline, just points. Think of it as Latin's "Voilà!" or "Check it out!"