Sincap çimenlerin arasında kaybolunca küçük kız çok şaşırdı.

It has two main parts:

• Sincap çimenlerin arasında kaybolunca = when the squirrel got lost / disappeared among the grass
• küçük kız çok şaşırdı = the little girl was very surprised

So the first part is a time clause and the second part is the main clause.

Also notice the subjects are different:

• sincap is the subject of kaybolunca
• küçük kız is the subject of şaşırdı

Kaybolunca comes from:

• kaybolmak = to get lost, to disappear
• -unca / -ince / -unca / -ünce = when / once / after

So:

• kaybolunca = when it got lost or when it disappeared

This suffix is very common in Turkish for expressing when something happens.

Examples:

• gelince = when he/she comes
• bitince = when it finishes
• görünce = when he/she sees

Because arasında usually works with a noun in the genitive form.

Here is the structure:

• çimenler = grasses / the grass
• çimenlerin = of the grass / of the grasses
• arasında = in between / among

So çimenlerin arasında literally works like in the space among the grass.

This pattern is very common:

• evlerin arasında = among the houses
• ağaçların arasında = among the trees
• insanların arasında = among the people

Here it means among.

In Turkish, arasında can mean both between and among, depending on context.

• With two things, English often uses between
• With many things, English often uses among

Since çimenlerin is plural, among the grass is the most natural translation here.

That is a very natural question for an English speaker.

English usually treats grass as an uncountable noun, but Turkish can use çimenler in places where English still just says grass.

So çimenlerin arasında is a normal Turkish way to say among the grass.

It does not necessarily mean separate countable grasses in a strict sense; it is just how Turkish often expresses this idea.

It can mean both, depending on context.

• to get lost
• to disappear
• to vanish from sight

In this sentence, because the squirrel is in the grass, the idea is probably that it disappeared from view in the grass or got lost among the grass.

So both ideas are close and natural here.

Because in Turkish, adjectives normally come before the noun they describe.

So:

• küçük kız = little girl
• büyük ev = big house
• güzel çiçek = beautiful flower

This is the same order as in English.

Also, adjectives in Turkish do not change form for singular/plural or gender.

Şaşırmak means to be surprised, to get surprised, or sometimes to be confused depending on context.

So:

• şaşırdı = was surprised / got surprised
• çok şaşırdı = was very surprised

Here çok means very or a lot.

With verbs, çok often translates naturally as very in English:

• çok sevdi = liked it very much
• çok korktu = was very afraid
• çok şaşırdı = was very surprised

Şaşırdı is in the simple past.

It is:

• şaşır- = verb stem
• -dı = past tense

So şaşırdı means he/she was surprised or got surprised.

This is the usual past tense for completed actions in a story.

You will often see this suffix in different forms because of vowel harmony and consonant changes:

• geldi
• baktı
• oldu
• gördü

Turkish does not have articles like English the and a/an.

So:

• sincap can mean a squirrel or the squirrel
• küçük kız can mean a little girl or the little girl

You understand which one is meant from the context.

In this sentence, English probably uses the squirrel and the little girl because they sound like specific participants in a story, but Turkish does not need separate words for that.

Yes. It is very natural Turkish word order.

The main clause is:

• küçük kız çok şaşırdı
• literally: little girl very was-surprised

Turkish often puts the verb at the end.

The time clause comes first:

• Sincap çimenlerin arasında kaybolunca...
• When the squirrel got lost among the grass...

That is also very common in Turkish. You could move parts around for emphasis, but this version sounds natural and straightforward.

Yes, and that is a useful comparison.

• kaybolunca = when it got lost / once it got lost
• kaybolduğunda = when it was lost / when it got lost

Both can translate as when, but -unca often feels a little more like once/when that happened, and it is very common in storytelling.

So kaybolunca is a very natural choice here. It gives the sense:

When the squirrel disappeared among the grass, the little girl was very surprised.