На земле лежало белое перо, и дочка положила его в книгу как закладку.

Земле is the prepositional singular of земля.

After на when it means location (on, at), Russian usually uses the prepositional case:

• на столе = on the table
• на полу = on the floor
• на земле = on the ground

So На земле tells us where the feather was lying.

Because it agrees with перо, which is a neuter singular noun.

• перо = neuter singular
• therefore лежало = past tense, neuter singular

In Russian past tense, verbs agree with the subject in gender and number:

• он лежал
• она лежала
• оно лежало
• они лежали

So лежало белое перо is literally structured as was-lying a white feather, but the verb still agrees with перо.

Because its subject is дочка, which is feminine singular.

Russian past tense verbs show gender in the singular:

• masculine: положил
• feminine: положила
• neuter: положило

So:

• перо лежало
• дочка положила

The two past-tense verbs have different endings because they have different subjects.

Because белое has to agree with перо.

Since перо is nominative neuter singular, the adjective must also be nominative neuter singular:

• белый = masculine
• белая = feminine
• белое = neuter
• белые = plural

So белое перо means white feather, with normal adjective-noun agreement.

Yes, Белое перо лежало на земле is also correct.

Russian word order is much freer than English, and it often changes focus rather than basic meaning.

• На земле лежало белое перо sets the scene first: On the ground, there was a white feather.
• Белое перо лежало на земле starts with the feather itself: A white feather was lying on the ground.

The original version sounds natural because it introduces the location first and then presents the new object.

Дочка is an everyday, affectionate, and very common form of дочь.

• дочь = daughter
• дочка = daughter / little daughter / dear daughter, depending on context

It does not always mean literally little. Very often it just sounds warmer and more natural in ordinary speech, especially when talking about a child.

Because его here means it, referring back to перо.

Even though перо is neuter, the object form of the personal pronoun is still его:

• он / оно → его in the accusative/genitive
• она → её

So:

• перо = neuter noun
• положила его = put it

This is normal Russian pronoun behavior. Personal pronouns do not simply copy adjective endings.

Because в can take different cases depending on whether you mean movement into something or location inside something.

• в книге = in the book → location, so prepositional
• в книгу = into the book → direction/movement, so accusative

Here the daughter puts the feather into the book, so Russian uses the accusative: в книгу.

Because this is a single completed action.

• положить = perfective, to put/place as a completed act
• класть / past клала = imperfective, more about process, repetition, or ongoing action

In this sentence, the daughter did one complete thing: she put the feather into the book. So положила is the natural choice.

Also note that the standard imperfective partner of положить is класть, not ложить in standard Russian.

Как закладку means as a bookmark.

The idea is that the feather is being used in the role of a bookmark. In this kind of practical, result-oriented construction, Russian often uses как + accusative:

• использовать что-то как инструмент
• взять это как пример
• положить его в книгу как закладку

So закладку is in the accusative singular.

A more formal alternative would be в качестве закладки, but как закладку is natural and common.

Yes. Закладка is the usual Russian word for a bookmark.

It comes from the idea of something inserted or placed in a book to mark a page. In this sentence, the feather is being used for that purpose.

Russian has no articles, so it does not have separate words for a and the.

Instead, the listener understands definiteness from context, word order, and the situation.

In this sentence:

• белое перо is being introduced for the first time, so English naturally says a white feather
• later, его refers back to that same feather, so English says it
• дочка may be understood as the daughter or simply daughter, depending on the broader context

So Russian leaves this information unstated unless there is a special need to make it explicit.