Question

1. A school is bigger than an elephant.

2. A school building is bigger than an elephant.

(Which one is right?)

3. She tried to write with a pencil.
4. she tried to write in pencil.

(Are both OK? Why do we not use 'a' after 'in'?)

Answer 1

All are correct.

Our use of articles seems to be more idiomatic than logical.