Learn Hardcore Russian: Дети любят прыгать в парке.

So они́ лю́бят → Дети любят… (“Children like …”).
Любить is the infinitive (“to love / to like”), and любят is the “they” form used with a plural subject like дети.

Why is прыгать in the infinitive? Why not conjugate it to match дети?

Russian uses the pattern любить + infinitive to say “to like doing something,” similar to English “like to do” / “like doing.”

So:

Дети любят прыгать. = Children like to jump / like jumping.

Grammatically:

любят is the finite verb, agreeing with дети (they).
прыгать is the infinitive, used as the object of любят (what do they like? → jumping).

You would not say “Дети любят прыгают” – that would be incorrect. After любить, you keep the second verb in the infinitive: любить делать что-то (“to like to do something”).

Why is it прыгать (imperfective), not прыгнуть (perfective)? Does aspect matter here?

Yes, aspect matters a lot.

прыгать – imperfective: to jump (in general, repeatedly, as an activity)
прыгнуть – perfective: to jump (once, a single act / completed action)

When you talk about liking an activity in general, Russian almost always uses the imperfective infinitive:

любить читать – to like reading
любить плавать – to like swimming
любить прыгать – to like jumping

Using прыгнуть here (любить прыгнуть) would sound wrong or at least very unnatural. You like the process / activity, not a single completed jump, so the imperfective прыгать is required.

What case is парке in в парке, and what is the basic (dictionary) form of this noun?

The dictionary form is парк (park), nominative singular.

In в парке, парке is in the prepositional case singular:

Nominative: парк – a park (subject form)
Prepositional: в парке – in the park

The prepositional case is used after certain prepositions, especially:

в – in
на – on / at

So в парке literally means “in (the) park” and answers the question где? (“where?”).

Why is it в парке and not в парк? What’s the difference?

The difference is location vs. direction (movement).

в парке – “in the park” (location, where something happens)
- прыгать в парке – to jump in the park (they are already inside the park, and the jumping happens there)
в парк – “to the park” (direction, where you are going)
- идти в парк – to go to the park
- ехать в парк – to drive / go to the park

In this sentence we describe where the children like to jump, not where they’re going, so Russian uses в парке with the prepositional case (location), not в парк (accusative of direction).

Could you explain the choice of в instead of на here? Why в парке, not на парке?

For most physical parks, Russian uses в (“in”) rather than на (“on / at”).

General patterns:

в is used with enclosed or defined spaces:
- в парке – in the park
- в доме – in the house
- в школе – at school / in school
на is used with surfaces, open areas, or certain set expressions:
- на улице – in the street / outside
- на площади – on the square
- на стадионе – at the stadium

So the natural phrase is в парке (“in the park”).
На парке would sound wrong in standard Russian in this context.

Can we change the word order? For example, is В парке дети любят прыгать also correct?

Yes, Russian word order is relatively flexible, and these are all grammatically correct:

Дети любят прыгать в парке.
В парке дети любят прыгать.
Дети в парке любят прыгать.

They all convey the same basic idea, but the emphasis shifts:

Дети любят прыгать в парке. – neutral, standard: Children like to jump in the park.
В парке дети любят прыгать. – emphasizes in the park (maybe contrasting with other places).
Дети в парке любят прыгать. – can sound like specifying which children (the ones in the park) or focusing on in the park as extra information.

The original sentence (1) is the most neutral and common in a textbook context.

Does любят mean “love” or “like” in this sentence?

Literally, любят comes from любить, which means “to love”, but in many contexts it is translated as “to like”, especially with activities and food.

Дети любят прыгать. – Most natural English: Children like jumping / like to jump.
Я люблю читать. – I like reading. (Context decides if it’s “love” or “like.”)

If you say Дети любят прыгать в парке, it doesn’t have to mean a deep emotional love; it just means that they enjoy doing that there. So “like” is the better translation here.

How would the sentence change if there was only one child: “The child likes to jump in the park”?

You would need a singular subject and singular verb:

Ребёнок любит прыгать в парке.

Changes:

Ребёнок (singular “child”) instead of Дети (plural “children”).
любит (3rd person singular) instead of любят (3rd person plural).

Structure:

Ребёнок – subject, nominative singular
любит – “he/she likes”
прыгать – to jump (infinitive)
в парке – in the park (prepositional case)

How do you pronounce this sentence, and where is the stress in each word?

With stress marks, the sentence is:

Де́ти лю́бят пры́гать в па́рке.

Stresses:

Де́ти – stress on де: DE-tee
лю́бят – stress on лю: LYU-b'yat
пры́гать – stress on пры: PRY-gat'
па́рке – stress on па: PAR-ke

A rough English-style pronunciation guide:

Де́ти – “DYET-ee”
лю́бят – “LYOO-b'yat”
пры́гать – “PRIH-gat'” (the ы is a bit like a hard “i” in “bit”, but further back)
в па́рке – “f PAR-ke” (the в before a consonant is often very short, almost like f)

Altogether: “DYET-ee LYOO-b'yat PRIH-gat' f PAR-ke.”

Could you leave out в парке? Would Дети любят прыгать still be correct?

Yes, Дети любят прыгать. is a completely correct and natural sentence.

Дети любят прыгать. – Children like to jump. (no place mentioned)
Дети любят прыгать в парке. – Children like to jump in the park. (adds location)

В парке is just an optional adverbial phrase of place. Removing it doesn’t break the grammar; it only makes the sentence less specific about where the jumping happens.