Prepositions are one of the biggest challenges for English learners. Even advanced students often feel unsure about when to use in or at, especially because many languages use only one equivalent preposition.

In this article, you will clearly understand:

• when to use IN
• when to use AT
• the real difference between good at and good in
• why both forms can be correct but mean different things

Let’s break it down step by step, with simple explanations and real-life examples.

When to Use AT in English

In general, AT is used to talk about:

• skills and abilities
• specific points or targets
• performance in activities

Because of that, AT is very common with verbs and adjectives related to ability, talent, and competence.

Examples with AT

• She is good at maths.
• He is great at football.
• I’m terrible at remembering names.
• She’s excellent at teaching children.

In all these examples, AT focuses on how well someone performs an activity or skill.

When to Use IN in English

On the other hand, IN often refers to:

• a field, area, or context
• a situation or environment
• behavior or qualities within a subject or role

So, IN is more about context, not performance.

Examples with IN

• She works in education.
• He is experienced in marketing.
• She behaved well in class.
• He’s respectful in his relationships.

Here, IN shows where or in which context something happens.

Good At vs Good In: What’s the Difference?

This is where many learners get confused, because both forms are grammatically correct, but they do not mean the same thing.

Understanding this difference will immediately make your English sound more natural.

Good At: Skill, Ability, Performance

Use good at when you are talking about:

• subjects
• sports
• skills
• activities
• performance

Examples

• I am good at football.
  This means you play football well.
• She is good at history.
  This means she understands the subject and performs well academically.
• He’s good at solving problems.
  This focuses on ability.

In short, good at = skill or competence.

Good In: Behavior, Character, or Role

Now, good in has a different idea. It is not about skill, but about behavior, suitability, or conduct within a context.

Examples

• He is good in history class.
  This suggests he behaves well or participates positively.
• She’s very good in her role as a leader.
  This refers to how she acts in that position.
• He’s good in difficult situations.
  This talks about attitude and behavior, not technical skill.

So, good in = behavior or quality within a context.

A Clear Comparison

Let’s compare the two:

• I am good at history.
  You are good at the subject itself.
• I am good in history.
  You behave well or have a positive attitude in that context.

That small change completely shifts the meaning.

Why This Difference Matters

Many learners say “I am good in English” when they actually mean “I am good at English.”
While the first sentence is not always wrong, it often does not express the intended meaning.

Using the correct preposition avoids confusion and makes your message precise.

A Simple Tip to Remember

Ask yourself one question:

Am I talking about ability or performance?
→ use AT

Am I talking about behavior, role, or context?
→ use IN

This simple check helps in most situations.

In School vs At School: What’s the Difference?

Another very common doubt among English learners involves the expressions in school and at school. Although they look similar, they express different ideas and are used in different situations.

Understanding this distinction helps you sound more precise and natural in everyday English.

At School: Physical Location

In most cases, at school refers to where someone is physically located at a specific moment.

In other words, it answers the question: Where is the person right now?

Examples

• She is at school right now.
• The children are at school until 4 p.m.
• I’ll meet you at school after class.

Here, at school simply means the person is inside the school building or on school premises.

In School: Status or Stage in Life

On the other hand, in school refers to being enrolled as a student or being in the phase of studying, not necessarily where the person is at that moment.

So, it talks about status, not location.

Examples

• She is in school, so she can’t work full-time yet.
• He’s still in school, finishing his studies.
• When I was in school, I hated maths.

Here is a video about a person being in the phase of studying

In these examples, in school describes a period of life or educational status, not a physical place.

A Clear Comparison

Let’s compare both meanings side by side:

• She is at school.
  She is physically there now.
• She is in school.
  She is a student, part of the education system.

Both sentences are correct, but they answer different questions.

Why This Difference Is Important

Many learners use in school when they actually mean at school, especially because other languages often use only one preposition.

However, using the wrong one can cause confusion or make your sentence sound unnatural.

Knowing this distinction improves:

• clarity
• precision
• natural fluency

A Quick Tip to Remember

Ask yourself:

Am I talking about location right now?
→ use AT

Am I talking about status, stage, or life situation?
→ use IN

This logic works not only with school, but also with many other expressions in English.