Breakdown of Дети сели на большое бревно.
большой
big
на
on, at / by (transport) / to (a place) / to (in answer to)
дети
children
сесть
to sit down
Questions & Answers about Дети сели на большое бревно.
The lesson mentions reflexive verbs for assuming a position, but why doesn't сели have a -ся or -сь ending?
The imperfective verb for taking a seat, садиться, is reflexive and has the -ся ending. However, its perfective pair, сесть (used here in the plural past tense as сели), is an exception and drops the reflexive ending. Because the action of sitting down was completed, we use the perfective сели.
Why do we use the accusative case for большое бревно instead of the prepositional case?
Verbs of assuming a position, like сесть, imply motion towards a destination (answering the question 'where to?'). When you move onto a surface, you use на followed by the accusative case. If the sentence instead described the stationary state of already being seated, it would use the prepositional case: Дети сидели на большом бревне (The children were sitting on a large log).
How do I know большое бревно is actually in the accusative case here, since it looks exactly like the dictionary form?
Бревно (log) is a neuter, inanimate noun. In Russian, inanimate neuter nouns (along with inanimate masculine nouns) have an accusative form that is completely identical to their nominative dictionary form. The neuter adjective большое follows this exact same rule.
If I wanted to say 'The children are sitting down on a large log' right now, which verb would I use?