Rising high school seniors should use the end of the school year to ask potential recommenders for a letter of recommendation on their behalf in the fall. While it may be too soon to formally request a letter of recommendation from a teacher and provide her with the necessary background information like a resume and your plans for college to write a quality letter, it is still an excellent opportunity to provide recommenders with notice that you would like to ask them to write on your behalf.
At many high schools with large class sizes, teachers may receive dozens of requests to write letters of recommendation. Great letters take time to write. The more notice a teacher has, the more they can plan accordingly and budget their time. If a teacher agrees to write a letter of recommendation on your behalf, ask her what materials she will need to write a strong letter. Many high schools have formal requirements for students to submit information packets to recommenders to help them write a recommendation, but a teacher may rely on specific information from students to write an insightful and compelling letter of recommendation.
The bottom line is, applicants, make the job as easy as possible on those who have agreed to help you, on their own time, get into college!