Salvēte, sodālēs.
Open up Lingua Latina Per Se Illustrata to page 7, Capitulum Primum.
(A capitulum, by the way, is a ‘chapter’. Primum has a primary meaning of ‘first’, but its meaning can range from ‘the beginning’ to ‘the most important.’ Here it means ‘first’. Capitulum Primum is ‘the First Chapter’.)
The chapter begins with a lovely illustration, with three features labeled - īnsula, fluvius and oppidum. These words, which identify an island, river and town, have been careful selected by the textbook’s author, Hans H. Ørberg. Each one is an example of a different type of noun.
For completeness, I’ve added nouns that end in -r. We can arrange these four noun types into families. Think of all the nouns that end in -us (fluvius, amīcus, equus, deus) as one type of noun. We will call them -us nouns. These nouns are closely related to the -r nouns (vir, puer). They are so closely related, that we might consider them siblings. -us nouns and -r nouns are masculine*. -um nouns like oppidum belong to the same family as -us and -r nouns, but are not quite so closely related. Lets think of them as cousins. -um nouns are neither feminine nor masculine. The grammatical term for that is ‘neuter’. Lastly, -a nouns (īnsula, amīca, equa, dea) belong to a totally different family. And -a nouns are feminine*.
* Usually. There are exceptions, but we won’t be seeing any for quite a while.
So, what does it mean that -a nouns and -us -r -um nouns belong to two different families? Nothing for now. But I’d like you to remember it for when I bring it up again later. Mostly I’d like you to appreciate that Ørberg has chosen these three words with great care.
Before you go, take a look at the map on page 6 (also below) and create a few Latin sentences of your own using īnsula, fluvius and oppidum. I’ll start: Corsica īnsula est. Nilus est fluvius. Oppidum est Sparta. Enjoy!