Prepositions: Time, Place, and Collocations

Quick rule: in = large time (year) → on = medium (day) → at = small (hour).

Quick rule: in = inside → on = touching a surface → at = a point.

"in" vs "on" for transport

"at" vs "in" for schools

• I study at a university. (at = at that institution)
• I'm in the classroom. (in = physically inside)

These are memorisation-only. Here are the highest-frequency ones for IELTS:

For Task 1, this matters: "There was an increase in sales" — not "increase of" (wrong) or "increase on" (wrong).

Mistake 1: Wrong preposition with time > ❌ I was born in May 15th. > ✅ I was born on May 15th.

❌ At 2024, the company expanded. > ✅ In 2024, the company expanded.

Mistake 2: Wrong preposition with verb > ❌ I depend of my parents. > ✅ I depend on my parents.

❌ We are discussing about the problem. > ✅ We are discussing the problem. (no preposition — discuss is transitive)

Mistake 3: Wrong preposition in Task 1 descriptions > ❌ The graph shows an increase of sales. > ✅ The graph shows an increase in sales.

❌ Sales increased of 20%. > ✅ Sales increased by 20%.

❌ Sales rose at $50 million. > ✅ Sales rose to $50 million. (endpoint) > ✅ Sales rose by 20%. (change) > ✅ Sales rose from $30 to $50 million. (range)

Fill in the correct preposition.

1. The meeting is ___ Monday ___ 10am.
2. She has worked here ___ five years.
3. I'm interested ___ learning Japanese.
4. Sales increased ___ 20% ___ the last quarter.
5. He's responsible ___ marketing.

Answers:

1. on / at •
2. for •
3. in •
4. by / in •
5. for

You have now completed all 10 lessons in Core Grammar. For best results, revisit these over 2–3 weeks rather than cramming — grammar improvement comes from repeated encounters, not one-time reading.