Tell me about a time you made a suggestion to improve business, to improve the quality/quantity of work in your last organization.

Two years ago I was working in school as an English teacher. There were 30-32 kids attending each class.
For one teacher during a 45min class, it was almost impossible to give attention to each and every kid and to make sure they understand all the material.
As I saw an issue, I have spoke to a director of a school. I asked if there would be a possibility to divide such classes to 15 kids per lesson, so it would give more time for each of them to interact with the teacher and ask questions.
In fact, this change was implemented. Both kids and parents were happy for that, as kids were able to advance in English much quicker

For replying to any behavioral interview question use the STAR method:

Listen carefully to the question and try to think of an event or situation.

S - Situation ( describe the situation or an event that happened to you);
T - Task ( describe the task that had to be completed );
A - Action (described an action completed by you in order to resolve an issue);
R - Result (finish your answer with the result achieved);

The STAR method give you a guaranty of present structure in your answer and will includes the information interviewer is looking for.