Learn Hardcore Swahili: Mistari uliyoiandika nyuma ya karatasi ni mifupi sana. - The lines you wrote on the back of the paper are very short.

Put the head noun outside the clause:
- mistari … (“the lines …”)
Then refer back to it inside the verb with an object marker:
- … uliyoiandika (“… that you wrote them”)

So:

Mistari uliyoiandika …
= “The lines that you wrote (them) …”

You could hear Mistari uliyoandika … in informal speech, but Mistari uliyoiandika … is the more careful, standard form because it clearly marks mistari as the object in the relative clause.

Why does the relative marker look like -yo- here? When do we use -yo-?

The -yo- in uliyoiandika is a short relative marker meaning “which / that”. It attaches to the verb after the tense marker:

u-li-yo-i-andika
you–PAST–RELATIVE–it–write

The actual form of the short relative marker depends on the noun class of the thing being described. For many non-human noun classes, including the class of mistari, the short form is -yo-.

Compare:

kitabu ulichoandika – “the book that you wrote”
(-cho- for kitabu, class 7)
chakula ulichokipika – “the food that you cooked (it)”
(-cho- again for class 7)
mistari uliyoiandika – “the lines that you wrote (them)”
(-yo- for mistari, a different class)

So -yo- here is simply the appropriate relative marker that agrees (in class) with mistari.

Why does mistari go straight into uliyoiandika without a separate word for “that/which”?

In Swahili, relative clauses are usually built by:

putting the relative marking inside the verb,
rather than using a separate word like English “that” or “which”.

So instead of:

“the lines that you wrote”

Swahili does:

mistari uliyoiandika
literally: “lines [you-PAST-REL-that-them-wrote]”

There is also a longer form using ambayo, e.g.:

mistari ambayo uliiandika nyuma ya karatasi
= “the lines which you wrote on the back of the paper”

Both are correct, but the short in-verb relative (uliyoiandika) is extremely common and more compact.

Is mistari singular or plural? How can I tell?

mistari is plural.

The singular is mstari = “a line”
The plural is mistari = “lines”

This noun follows the m-/mi- class (class 3/4) pattern:

mstari (sg.) – starts with m-
mistari (pl.) – starts with mi-

Clues that it’s plural in the sentence:

The ending -i in mistari is typical for plural of this class.
The adjective mifupi also has mi-, which is the plural agreement for this class.

Why is the adjective mifupi and not just fupi?

Swahili adjectives usually agree with the noun class and number of the noun they describe.

Noun: mistari (plural, m-/mi- class)
Adjective root: -fupi (“short”)

For this class:

Singular (mstari): mfupi – mstari mfupi (“a short line”)
Plural (mistari): mifupi – mistari mifupi (“short lines”)

So in the sentence, mistari … ni mifupi sana, the adjective must match the noun:

mistari (plural, mi-)
mifupi (plural adjective with the same mi- prefix)

Using just fupi without mi- would break the agreement pattern and sound wrong here.

What is the role of ni in this sentence? Is it the verb “to be”?

Yes. In Mistari uliyoiandika nyuma ya karatasi ni mifupi sana, the ni is a copula, functioning like the English verb “to be”:

Mistari … ni mifupi sana
“The lines … are very short.”

Some points about ni:

It does not change for person or number:
- mimi ni …
- wewe ni …
- mistari ni …
It’s not used in all tenses (e.g. for present habitual with verbs you just use the verb), but with nouns/adjectives in simple present like this, ni is the normal way to say “is/are”.

What does nyuma ya karatasi literally mean? Does it mean “behind the paper” or “on the back of the paper”?

Literally:

nyuma = “back / behind”
ya = “of” (linking word; see below)
karatasi = “paper / sheet of paper”

So nyuma ya karatasi literally is “the back/behind of the paper”.

In context, it most naturally means:

“on the back (side) of the paper”
rather than “physically located behind a sheet of paper somewhere.”

Swahili often uses nyuma ya X to mean:

the back side of a physical object (e.g., nyuma ya karatasi, nyuma ya nyumba),
or “behind X” in a more spatial sense, depending on context.

Why is it nyuma ya karatasi and not nyuma la karatasi or nyuma wa karatasi?

The linking word ya / wa / la / cha / vya / etc. is the genitive connector (often glossed as “of”), and it must agree with the class of the first noun.

Here:

nyuma is a noun in class 9/10.
The genitive form for class 9/10 is ya.

So:

nyuma ya karatasi = the back/behind of the paper

If the first noun were in a different class, the genitive would change, for example:

mti wa nyumba – “the tree of the house” (mti = class 3 → wa)
gari la mwalimu – “the teacher’s car” (gari = class 5 → la)

Because nyuma is class 9, you must use ya, not wa or la:

✔ nyuma ya karatasi
✖ nyuma la karatasi
✖ nyuma wa karatasi

Why isn’t there any word for “the” or “a” in mistari or karatasi? How do I know if it means “the lines” or “some lines”?

Swahili does not have articles like English “a/an” and “the”. Nouns like mistari and karatasi are bare; their definiteness (“the vs some”) is understood from context.

mistari uliyoiandika nyuma ya karatasi
can mean:
- “the lines that you wrote on the back of the paper”
  or
- “the lines you wrote on the back of a paper / some paper”

In this sentence, because we’re talking about specific lines on a specific paper that both speakers know about, English naturally translates it with “the”.

Swahili relies on:

context,
sometimes demonstratives (hii, ile, hayo, etc.) for emphasis,

rather than definite/indefinite articles like English does.

Can I move nyuma ya karatasi to another position in the sentence, or must it stay exactly where it is?

You have some flexibility. The original is:

Mistari uliyoiandika nyuma ya karatasi ni mifupi sana.

You could also say, for example:

Mistari uliyoiandika ni mifupi sana nyuma ya karatasi.
(grammatically okay, but sounds odd; it seems to say the shortness is “on the back”)

Much more natural alternatives keep nyuma ya karatasi close to the verb andika, because it is describing where you wrote the lines:

Mistari uliyoiandika nyuma ya karatasi ni mifupi sana.
Mistari uliyoiandika kwenye nyuma ya karatasi ni mifupi sana. (less natural; often kwenye is dropped here)

Putting it before the relative clause, like:

✖ Mistari nyuma ya karatasi uliyoiandika ni mifupi sana

is not good, because nyuma ya karatasi belongs logically with kuandika (“to write”), not with mistari alone.

So yes, word order has some room, but the best place for nyuma ya karatasi is right next to the verb it modifies (here, liandika).

Is the object marker -i- in uliyoiandika absolutely necessary, or can I say Mistari uliyoandika nyuma ya karatasi?

In careful, standard Swahili, when:

the head noun (mistari) is
the direct object in the relative clause (“that you wrote”),

it is strongly preferred (and often considered required) to include the object marker in the verb:

✔ Mistari uliyoiandika nyuma ya karatasi …

Without the object marker:

Mistari uliyoandika nyuma ya karatasi …

you will still be understood, and many speakers do say this in informal speech, but many grammar descriptions treat that as less correct or at least less elegant.

So for good, reliable Swahili (especially writing or exams), use:

Mistari uliyoiandika … (with -i-).

Why doesn’t karatasi change form here? How do I know if it’s singular or plural?

karatasi belongs to a noun class (9/10) where singular and plural often look the same:

karatasi = “paper / sheet of paper / papers”

The number is usually inferred from:

Context:
- Here, we naturally imagine one sheet of paper someone wrote on.
Agreement (adjectives, verbs) – though in this sentence, we don’t have an adjective directly modifying karatasi, so context carries most of the load.

So:

nyuma ya karatasi most naturally means “on the back of (the) paper / (a) sheet of paper”, but formally it could also be “on the backs of papers”; you’d specify more if the context needed it.