The very first full Polish sentence most learners ever produce is To jest… ("This is… / That is…"). It is how you point at something and name it: To jest dom ("This is a house"), To jest moja siostra ("This is my sister"). The construction looks trivial, but it hides the single most useful early grammar distinction in Polish — the contrast between to jest (point-and-name, predicate in the nominative) and a personal subject with być (predicate in the instrumental, as in On jest nauczycielem). Get this contrast straight at A1 and you avoid an error that haunts learners for months.
The pattern: to jest + nominative
The skeleton is To + jest + a noun in its dictionary (nominative) form.
To jest dom.
This is a house.
To jest moja siostra.
This is my sister.
To jest dobra książka.
This is a good book.
Notice what does not happen. The noun after jest is in its plain dictionary form: dom, siostra, książka — exactly as you would find it in a dictionary. There is no case change. This is genuinely different from the other "X is a Y" sentence Polish builds (see below), and the difference is the whole reason this page exists.
The word to here means "this" or "that" used as a pointing word — like jabbing your finger at something and saying "this". It is not the subject "it" in the English grammatical sense; it is a presentational gesture frozen into a pronoun. For the demonstrative pronoun to in its full role, see ten / ta / to.
to is invariable — even before a plural
Here is the first thing that surprises English speakers, who are used to "this is" vs "these are". In Polish, to does not change for number or gender. Before a plural noun you still say to, only the verb becomes są ("are"):
To są moje książki.
These are my books.
To są moje dzieci.
These are my children.
To są nasi sąsiedzi.
These are our neighbours.
You might have expected te są… (with the plural demonstrative te), by analogy with English "these". Resist it. In the identifying construction, to is frozen — it is the same invariable to whether what follows is masculine, feminine, neuter, singular, or plural. Only jest → są flips for number. (The plural te does exist, but it modifies a noun directly: te książki "these books" — a different structure, not the to jest pattern.)
The crucial contrast: To jest nauczyciel vs On jest nauczycielem
This is the heart of the page. Polish has two ways to say "X is a teacher", and they use different cases for "teacher":
| Pattern | Sentence | Case of predicate | Use |
|---|---|---|---|
| Pointing / identifying | To jest nauczyciel. "This is a teacher." | Nominative (nauczyciel) | Point at a person/thing and name it |
| Personal subject + być | On jest nauczycielem. "He is a teacher." | Instrumental (nauczycielem) | State a role/profession of a known subject |
Both are correct Polish; they are not interchangeable styles of the same sentence. The first introduces an entity ("Look — a teacher"); the second predicates a role of an already-identified person ("He works as a teacher").
To jest nauczyciel. On jest bardzo miły.
This is a teacher. He is very nice.
To jest lekarz, a to jest pielęgniarka.
This is a doctor, and this is a nurse.
Mój brat jest inżynierem.
My brother is an engineer.
In the last sentence the subject is mój brat (a real noun subject), so the predicate inżynier goes into the instrumental: inżynierem. The moment you have a genuine subject — a name, a pronoun, a noun phrase — Polish switches the predicate noun to the instrumental with być. For the full logic of why, see the instrumental predicate and the nominative predicate.
Why the split? The English verb "to be" does one undifferentiated job. Polish, by contrast, distinguishes presenting something to your interlocutor (nominative — you are handing over a label) from characterizing a subject already in play (instrumental — you are assigning it to a category). The instrumental is the case of "in the capacity of, as", so On jest nauczycielem literally frames "he" as existing in the capacity of a teacher.
jest can be dropped
In everyday speech the jest is often left out, leaving just To + noun:
To moja siostra.
This is my sister.
To mój nowy telefon.
This is my new phone.
To prezent dla ciebie.
This is a present for you.
The dropped-verb version is slightly more casual and extremely common in conversation. The predicate stays nominative either way — dropping jest changes nothing about the case. You will hear both To jest moja siostra and To moja siostra from the same speaker minutes apart.
The question forms: Co to jest? and Kto to jest?
To ask "What is this?" you front the question word and keep the frozen to (jest):
Co to jest?
What is this?
Co to jest? — To jest słownik.
What is this? — This is a dictionary.
Kto to jest?
Who is this?
Kto to? — To moja koleżanka z pracy.
Who's this? — This is my colleague from work.
Notice that Kto to? routinely drops jest in speech, just like the statements do. The answer mirrors the question's structure: a question with to jest is answered with to jest, predicate in the nominative. For the interrogatives themselves, see kto / co.
Common Mistakes
❌ To jest nauczycielem.
Incorrect — the identifying 'to jest' takes the nominative, not the instrumental.
✅ To jest nauczyciel.
This is a teacher.
❌ On jest nauczyciel.
Incorrect — a personal subject with być needs the instrumental.
✅ On jest nauczycielem.
He is a teacher.
❌ Te są moje książki.
Incorrect — the identifying word stays the invariable 'to', not the plural 'te'.
✅ To są moje książki.
These are my books.
❌ To jest moje dzieci.
Incorrect — a plural predicate needs 'są', not 'jest'.
✅ To są moje dzieci.
These are my children.
❌ Co jest to?
Incorrect word order — the question word fronts, then 'to jest'.
✅ Co to jest?
What is this?
Key Takeaways
- To jest… (singular) / To są… (plural) is the point-and-name construction; the predicate noun stays nominative (dictionary form).
- to is invariable — it never becomes te before a plural; only the verb changes (jest → są).
- Contrast it with a real subject + być, which puts the predicate in the instrumental: On jest nauczycielem, Mój brat jest inżynierem.
- jest is freely dropped in speech: To moja siostra, Kto to?
- Questions: Co to jest? ("What is this?"), Kto to (jest)? ("Who is this?").
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Start learning Polish→Related Topics
- Nominative in Predicates and NamingA2 — When 'X is Y' keeps the nominative — after to and in naming, labels and titles — versus when Polish demands the instrumental, with the decisive to/instrumental split.
- Instrumental as Predicate (Jestem nauczycielem)A2 — Why 'I am a teacher' is jestem nauczycielem (instrumental) — the predicate noun after być, zostać and okazać się — and why a predicate adjective (jestem zmęczony) stays nominative.
- być — to beA1 — Complete reference for być ('to be') — the most essential and most irregular Polish verb: full present, past (by gender), future, imperative, conditional and verbal-adverb tables, plus its three predicate patterns.
- Demonstratives: ten, ta, to, ci, teA1 — ten 'this' agrees in gender, number and case like an adjective — but the sentence-opening to in 'to jest…' is a frozen, invariable word that does not agree at all.
- to: This Is, That Is, These AreA1 — The frozen identifying to (To jest…, To są…, To moja siostra) that never inflects — how it points and names, and how it differs from the agreeing neuter to in ten/ta/to.