Latin/First Declension (L2)
First Declension 
The first declension is a group of Latin nouns with the same endings. It is the most regular of the five declensions, in that the twelve endings (6 cases X 2 numbers) are always exactly the same. All you need to do is find the stem. Most first declension nouns are feminine, though a few notable exceptions are masculine.
Case Endings 
We've already seen the first declension in the charts in the introduction to nouns, but let's take a closer look now.
First, the singular:
Now, the plural:
You will have to memorize these endings; you should do this now. Memorize all twelve endings even though this lesson will only use four (nominative singular, nominative plural, accusative singular, accusative plural).
Finding the Stem 
How do we determine what the stem (i.e., the part before the ending that remains the same in each case) is and what the ending is? Well, we go back to the dictionary entry that we learn for each word. First, we need to check to see if we have a first declension noun. If the nominative singular ends in -a and the genitive singular ends in -ae, we have a first declension noun.
- mensa, mensae, f. Table.
- puella, puellae, f. Girl.
Note how both of those words have the endings that we just said were marks of the first declension nouns. Knowing that -ae is the ending for the genitive singular, all we need to do is delete that ending from the word. So, mensae loses the -ae and becomes mens-. That is what is known as the stem of the word. You can add the necessary ending for whatever case and number is needed to that stem. So, if you want an ablative plural (case ending -is), you would just add that ending to mens- to get mensis.
Dictionary Convention 
Often, dictionaries will shorten the entry by just printing the genitive singular ending instead of the entire genitive singular. So, "table" and "girl" will appear as:
- mensa, -ae, f. Table.
- puella, -ae, f. Girl.
If you see the -ae notation in an entry, it is clear that the word is a first declension noun.
Nominative Case 
The nominative, or "name" from the Latin nomen, case is almost always used for the subject of a sentence. For instance, in the sentence "Julia gives" the subject is Julia (what she gives and to whom she's giving it, we don't know). She's the one doing the action. So, if the sentence were in Latin, Julia would have to be in the nominative case. Even in a more complex sentence such as "Julia hesitantly decided that it would be a wonderful idea to destroy the table by repeatedly kicking it", we can still find the subject fairly easily. It's still Julia doing the action.
Now, we're not even going to try translating that second sentence into Latin quite yet. But, we know most of what we need to know to translate the first one. First, we need to know how to say Julia in Latin. Luckily for us, many women's names were treated as first declension nouns in Latin, so:
- Julia, -ae, f. Julia.
Julia has a stem of Juli- and in the nominative singular (nominative because Julia's the subject, singular because there's only one Julia) the ending is -a. Therefore, we have Julia.
"Julia gives" 
We haven't learned any verbs yet and there is a lot to learn about verbs before they can be used well, but for our purpose right now we will just say that dat means "gives". So, if we want to say "Julia gives", the sentence in Latin is:
- Julia dat.
Your first Latin sentence! Pretty simple, huh? Well, let's add on to it.
Accusative Case 
The accusative case is often the direct object of a sentence. Take this sentence: "The boy reads a book." We know from our discussion on the nominative case that "the boy" is the subject. "Reads" is our verb, so the boy is reading something. The answer to the question "What is the boy reading?" is the direct object. In this case, the boy is reading a "book". "Book", then, is our direct object and would be in the accusative case in Latin.
"Julia gives a table" 
So, going back to our earlier sentence with Julia, let's pick something for Julia to give. Maybe Julia has a lot of tables and wants to get rid of one. We still don't know who is going to get this table, but we can say "Julia gives a table." Recall that table is:
- mensa, -ae, f. Table.
So, knowing that the stem of the word is mens- and the accusative single ending is -am, the table that Julia gives would be mensam. Because the article "a" from "a table" does not translate into Latin, we know all three of the words we need for our short sentence (dat, Julia, and mensam). But what order do they go in? In all actuality, the words could go in any order and you would be able to translate the sentence, because the case of each of the nouns tells you what its usage is. So, even if we said, "Mensam dat Julia.", you would know that the table cannot be the subject.
In actual Latin, the most common sentence structure is nominative-accusative-verb. Compare this to English subject-verb-object. So, if we use the Latin word order, we get:
- Julia mensam dat.
- Julia gives a table.
Note that if we decide Julia has to get rid of more than one table, we could say:
- Julia mensas dat.
- Julia gives tables.
The Accusative Case is:
- Singular Plural
f.-am -as m.-us -os n.-um -a
"The table gives Julia" 
If we wanted to turn the tables (excuse the pun) and say that the table gives Julia (completely nonsensical, I know, but grammatically correct), we would have to put "Julia" in the accusative (Juli-am) and "table" in the nominative (mens-a). Then, we would get:
Mensa Juliam dat. The table gives Julia.
So far we've learned:
- mensa, -ae, f. table
- puella, -ae, f. girl
- Julia, -ae, f. Julia
Let's add a couple more. Make sure you memorize the three above as well as these two following.
- sapientia, -ae, f. wisdom
- poeta, -ae, m. poet
Wait a minute! Take a look at "poet" again. See something odd? It's not feminine! Poet is one of the few first declension nouns that are masculine. You don't really need to worry about that too much quite yet, because it does not affect how the noun is used. Later, when we get into adjectives and other things, you will need to know what each noun's gender is. For now, use poeta like you would any of the others and just keep its masculinity in the back of your mind.
With those vocab words and translating dat as "gives" and amat as "loves", translate the following sentences.
- Poeta sapientiam dat.
- Poeta puellas amat.
- Julia poetas amat.
- Sapientia mensas dat.
- Puella Juliam amat.
Congratulations! You now know four common nouns and one name! You know the case endings for every single first declension word, so that even if you come across one that you've never seen before, you will know what case and number it has. Yo