Kısacası plan işe yaradı.

Yes—it's best to learn Kısacası as a set phrase.

It is a very common discourse marker meaning things like in short, briefly, in a nutshell, or long story short. It does not describe the verb directly; instead, it comments on the whole sentence and signals that the speaker is summarizing.

So in this sentence, Kısacası sets up the final takeaway.

They are close, but not identical.

• kısaca = briefly / briefly speaking
• kısacası = in short / the short of it is / basically

In many situations, both can work, but kısacası sounds more like a summary or conclusion after some explanation.

So:

• Kısaca plan işe yaradı. = Briefly, the plan worked.
• Kısacası plan işe yaradı. = In short, the plan worked.

The second one more clearly signals this is my conclusion.

Turkish does not have definite and indefinite articles in the same way English does.

So plan can mean:

• the plan
• a plan

The context tells you which one is intended.

If Turkish wants to make it clearly indefinite, it can use bir:

• bir plan = a plan

But a bare noun like plan is very normal, and in many contexts English will translate it as the plan.

işe yaradı comes from the verb işe yaramak, which is a very common expression meaning:

• to work
• to be useful
• to be effective
• to do the trick

It is often used for plans, ideas, methods, medicine, tricks, tools, and solutions.

So plan işe yaradı means the plan was effective or achieved its purpose.

Because the expression is işe yaramak, not iş yaramak.

Here, işe is iş plus the dative ending -e. In this expression, the dative is required.

So you should learn it as a whole chunk:

• işe yarıyor = it works / it is useful
• işe yaradı = it worked
• işe yarayacak = it will work

Even if the literal logic is not obvious at first, the safest approach is to memorize işe yaramak as one unit.

yaradı is the simple past form of yaramak.

Breakdown:

• yara- = verb stem
• -dı = past tense suffix

So:

• yarıyor = is working / is useful
• yaradı = worked / was useful
• yarar = works / is useful

The past tense suffix appears as -dı here because of vowel harmony and normal consonant choice.

Not always.

They can both sometimes be translated as worked, but they are used differently.

• çalıştı usually means operated, functioned, or was running
• işe yaradı usually means was effective, was useful, or achieved the intended result

For example:

• Makine çalıştı. = The machine worked / operated.
• Plan işe yaradı. = The plan worked / was effective.

A machine often çalışır.
A method, medicine, excuse, or plan often işe yarar.

Turkish word order is flexible, but this order is very natural.

• Kısacası comes first because it frames the whole statement as a summary.
• plan is the subject.
• işe yaradı is the predicate.

Starting with Kısacası is similar to beginning an English sentence with In short or Basically.

You could move things around in some contexts, but this version sounds smooth and standard.

You can, but it is less neutral.

Putting kısacası at the end can sound like an afterthought or a spoken-style wrap-up. Starting with Kısacası is the more typical way to present a summary clearly.

So for a textbook-style sentence, Kısacası plan işe yaradı is the best choice.

A rough guide:

• Kısacası: kuh-sah-jah-suh
• plan: similar to English plan
• işe: ee-sheh
• yaradı: yah-rah-duh

A few important sound notes:

• ı is the Turkish dotless i. It is not the same as English ee.
• ş is like sh
• c in Turkish is like English j in jam

So the c in Kısacası is pronounced like j, not like English k or s.

Yes.

Some common alternatives are:

• Kısacası plan işe yarıyor. = the plan is working
• Kısacası plan işe yarar. = the plan works / is effective
• Kısacası plan işe yarayacak. = the plan will work

In your sentence, yaradı shows that the success happened in the past.

It is somewhat idiomatic.

The verb işe yaramak is a standard Turkish expression that learners should treat as a fixed collocation. Even though you can analyze the words separately, native speakers process it as a normal phrase meaning to be effective / to work.

So instead of translating it word by word every time, it is better to store:

• işe yaramak = to work / to be useful / to do the trick