Let’s compare the two sentences below :

1) In scholā sunt = They are in the school

2) In īnsulā sunt = They are on the island

In the first sentence “In” means “in” in English, but in the second sentence “In” means “on” in English. Also, the words that modified “In” like scholā and īnsulā are all in the ablative.

“In” can take on another meaning :

Servus in casam ambulat = The servant is walking into the house

In this sentence “in” takes on the meaning of “into”. However unlike the other two sentences, the nouns that modify “in” are in the accusative.

How can you determine which “in” is being used? If the word that modifies the “in” is in the accusative, you know that it means “into”. When the word that modifies “in” is in the ablative, choose whichever meaning (in or on) that makes the most grammatical sense.

Time to practice!

1) Puerī in castrīs sed agricolae in agrīs

2) Puellae in silvam ambulant et in oppidum ambulāmus

3) Virī in semper īnsulā sed fēminae in numquam īnsula

Here are the answers :

1) The boys are in the forts but the farmers are in the fields

2) The girls are walking into the forest and we are walking into the town

3) The men are always on the island but the women are never on the island