Each school will submit a letter of introduction to the project. We would appreciate your limiting the letters to one per school. Letters can be any length. Some teachers have their class as a whole write the letter and other teachers assign it to a couple of students. Or you may have everyone take a stab at the letter and then select the best one.
Some teachers even write the letter themselves.
Do whatever is best for you. Feel free to look at examples from last year's project. Letters of Introduction should be submitted to the project Discussion Area.